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Dr. Tarbox: Hello, and welcome to "Skincast," the podcast for people who want to learn how to take the very best care of the skin they're in. My name is Michelle Tarbox. I'm an associate professor of dermatology and dermatopathology at Texas Tech University Health Sciences Center in beautiful sunny Lubbock, Texas. And joining me is . . .

Dr. Johnson: Hi, everybody. This is Dr. Luke Johnson. I am a pediatric dermatologist and general dermatologist with the University of Utah in Salt Lake City.

Dr. Tarbox: Today, we're going to talk about a condition that's relatively common and affects a significant proportion of the population when you look at everything writ large. So we're going to talk about psoriasis. Luke, what is psoriasis?

Dr. Johnson: Psoriasis is a red, scaly rash. A lot of things in dermatology are red, scaly rashes. Psoriasis is pretty common though, so you may have seen somebody with it, or I suppose you might have it yourself. It affects 1% to 3% of the population, which means if you pulled 100 people out at random, 1 to 3 of them would have psoriasis.

The red, scaly rash of psoriasis often has thick, white scale over the top of it. And it likes to affect certain parts of the body. It likes the elbows and the knees and the scalp.

Dr. Tarbox: It has two peaks of onset. You probably see one of them more and I probably see the other one more frequently. What is the peak that you see?

Dr. Johnson: So mid to late adolescence/really early young adulthood, psoriasis tends to show up.

Dr. Tarbox: Yeah. And it's one of those conditions that can come up at any point in a person's life, but it is more common at certain ages.

Dr. Johnson: And it just shows up. And then middle age, like in the 50s, is the other time when it tends to arise.

Before I went to medical school, I got psoriasis and cirrhosis confused all the time. So cirrhosis, first of all, is spelled with a C, whereas psoriasis is spelled with a P. Neither of them are spelled with an S at the beginning, which is absurd. Thanks, language. But cirrhosis is a liver disease and psoriasis is the skin disease.

Dr. Tarbox: And I think a lot of the confusion sometimes comes from the fact that many of our medical words originate in the Greek language. So the word psoriasis is actually from a word in Greek that sounds to us now like psora, and then -iasis means condition. So psora means itch or rash that's sort of itchy, and -iasis is a condition.

The term cirrhosis also from the Greek is from the word "kirrhos" in Greek, which is the yellowish color of the skin and the liver that occur in that condition. But they're not really necessarily interrelated with each other.

Dr. Johnson: So, because psoriasis is so common, you might wonder if there are some fancy celebrities out there who have it. And indeed, there are. So just having psoriasis doesn't mean you can't become a celebrity and achieve great things. The following celebrities have psoriasis: Kim Kardashian, Kris Jenner, Cyndi Lauper, Phil Mickelson, the golfer, LeAnn Rimes, Art Garfunkel, Jon Lovitz, and John Updike.

Dr. Tarbox: Also, CariDee English, who was an America's Next Top Model winner, has psoriasis and has been a spokesperson with the National Psoriasis Foundation. And I actually got to meet her and she was so kind and took a picture with me. She's a very sweet person.

But having these celebrity relatable characters that we can kind of illustrate to some of our young patients especially that have psoriasis how full and complete of a life you can have with the condition on the skin is very helpful.

And I think that especially pointing to somebody who's used her position to be more of an advocate for people with the condition like CariDee English really is helpful for young patients.

Dr. Johnson: So what causes psoriasis? Well, there has been a whole bunch of research on that in the last 20 to 25 years, and it is super complicated. Michelle and I look at these medical journals and there are these big diagrams with lots of pictures of cells and arrows going all over the place and a bunch of letters and numbers, and it's just a complete mess. But the good news is that after sorting out some of the mess to some degree, that allows us to develop new medications that impact the causes of psoriasis.

In broad terms, I like to think of psoriasis as an immune dysregulation. The immune system is hanging out in the skin, but it's not doing what it is supposed to.

There are some dermatologists who think that it is autoimmune. I feel like the science has not told us that it is definitely autoimmune yet. It's possible that it will in the future. So I like to refer to it as an immune dysregulation.

Dr. Tarbox: And I think that that's a great way to think about it because the immune cells are activating inflammatory pathways that they're supposed to use to fight bacteria, or viruses, or maybe cancer against normal skin and creating this inflammatory state that then has to be treated.

Dr. Johnson: Well, why do some people get it and some people don't? Why does some people's immune system get dysregulated in this way? We think that there are genes, and there's definitely some genes that have been associated with psoriasis, but like many of the other diseases we talk about, it's not a strict familial inheritance. It's not like if you have it, then your child definitely has it. A lot of times, actually, only one person in the family has it.

And there are certain types of medications that can cause it as well. These are generally medications that your doctor would have prescribed to you for some other reason. But especially in the middle-aged and older age group, if you suddenly develop psoriasis, then I hope that your doctor is looking at your medication list and making sure it wasn't one of those that could have caused it. It can even be a medication that you've been on for a year or two. It's not, "I took this new medication and then suddenly I have psoriasis."

And then kind of vitiligo, which we have also talked about on the podcast, psoriasis can exhibit this Koebnerization phenomenon, again, described by Dr. Heinrich Koebner in the 1800s, which is when a disease goes to sites of injury. So people with psoriasis if they get a big scratch on their leg, for example, they can discover that there is then a line of psoriasis that appears there.

But fear not, there are treatments, and Michelle is super pumped to talk about them.

Dr. Tarbox: So pumped right now. So pumped. The ways that we can treat it . . . Of course, if you have mild psoriasis, knowing Koebnerization, that trauma homing that this condition can do, can kind of worsen the disease, gentle skin care is very helpful.

A lot of times when Americans have a skin condition, we tend to want to try to beat it out of the skin with harsh chemicals. We see this a lot with acne where people will put everything they can find on their skin to try to treat acne, including mouthwash and toothpaste, and sometimes even dish soap and things that are a little bit more harsh.

In general, being more gentle with your skin is almost always the right way to go, and definitely the case here in psoriasis. Of course, there are some topical medications that we sometimes use, both over-the-counter strength topical steroids like hydrocortisone 1% for more minor psoriasis, and then prescription-strength topical steroids with a physician.

Dr. Johnson: Topical, of course, means a cream or an ointment, something you put on top of the skin and then rub in.

Psoriasis is one of the diseases that responds to phototherapy, which we've discussed before on the podcast, a special wavelength of light that can help the skin. In fact, psoriasis is probably the best-studied disease for phototherapy treatment.

And then, again, because the immune system is dysregulated, one option is to just tell the whole immune system to chill out. So we have these immune-suppressing medications that work, but have potential side effects, as you might guess.

As I mentioned, because we're further understanding what we call the pathogenesis of psoriasis, why it happens from a cellular level, new medications have also been developed recently.

Dr. Tarbox: So, in rare circumstances, we can also sometimes treat patients for a coexistent over-colonization with strep with antibiotics to help their psoriasis improve if the strep triggered the condition, which can rarely happen. That's more common with younger patients and more common with much smaller plaques of psoriasis, something we call guttate psoriasis. That word guttate means rain drop-like. And so in that particular condition, we might use oral antibiotics to decrease the strep colonization in those patients.

Now, very importantly, psoriasis is not infectious. It's not contagious in any way. It can occur within many members of one family because of genetic predisposition, but it's not something people pass one person to another. And that's very, very important, especially for patient well-being. I have some patients who've actually been kicked out of public pools or asked to leave daycares because people don't understand the condition and think it might be contagious, but it is not.

Dr. Johnson: And again, with these fancy new medicines, it's very treatable. It's hard for me to overemphasize how great these new medicines are. They're really a triumph of medical and pharmaceutical science. Understanding the way psoriasis works allows pharmaceutical manufacturers to create molecules that interfere very specifically with pathways that have gone wrong in psoriasis.

So we cannot cure the disease. I'm sorry. Perhaps one day we will. But we can give somebody an injection perhaps just every three months, which basically clears their disease with almost no side effects, which is not a cure, but still awfully darn good.

Of course, as you might guess, the main downside of these fancy new medications is how expensive they are. But if you have or know somebody who has significant psoriasis, these are gangbuster medications. And it also gives the whole dermatologic field a lot of hope for some of our other diseases that have been problematic, things like eczema and vitiligo and alopecia areata, that we might also develop similar medications for them.

Dr. Tarbox: There are patient support charities that help people afford the medications to treat their psoriasis when they qualify. So if you're a person who has significant psoriasis and you don't have insurance coverage, or you don't have the financial means to get the medication, you may be able to get it through one of the support foundations.

And then a lot of my patients like to ask me about what kinds of things that they can do with their general health to improve the state of their psoriasis. And I love when they ask that question because our general state of health significantly influences the course of psoriasis, and modifications to our diet and behavior can help improve the condition and its response to treatment.

So we know for a fact that psoriasis is a pro-inflammatory condition. Things that we eat or take into our body that cause more inflammation can worsen psoriasis, so highly processed foods, foods with a lot of sugar in them. Alcohol we know is one of the things that can push on psoriasis, as can smoking.

Patients who have psoriasis that are more active and who stick with a healthier diet have an easier time controlling their disease and have less extensive disease.

Now, we know that the psoriasis can make it hard to have a healthy lifestyle. The psoriasis plaques can make it harder to exercise sometimes. If you are a person who's uncomfortable showing the skin that has psoriasis on it, there may be some activity limitation because of the need to cover.

However, the skin of psoriasis is, besides the inflammation, normal skin. It's not any more likely than your normal skin to get infected. Actually, it may be less likely to get a skin infection than your normal skin. And it's not something you're going to pass to anybody else. So letting that skin be open to the air is not a damaging thing at all and is not going to put you or anybody else at any kind of danger.

But I do always encourage my patients who have psoriasis to try to be as healthy as possible. We also know that things that are anti-inflammatory like turmeric can help that. We know that some studies have actually looked into the addition of other supplements like ox-bile supplements to help improve the metabolism of certain fats in the gut.

But what are some things that patients need to worry about with psoriasis, Luke?

Dr. Johnson: Well, all of those lifestyle factors are a good idea because we know that psoriasis is associated with an increased risk of cardiovascular disease, things like heart attacks and strokes and so on. So somebody with psoriasis compared to somebody who's exactly the same, same weight, same blood pressure, same exercise level, and everything, if those two people are compared, the person with psoriasis has a greater risk of developing something like a heart attack or a stroke. It's a bummer, but it's true.

So people with psoriasis, I always encourage them to . . . It's an extra reason to stay on top of your blood pressure and your cholesterol and have a healthy activity level and a healthy weight and stay plugged in with your primary care physician and so on.

Good news is that this one and a lot of the other things that we know can also occur in people with psoriasis. The worse your psoriasis, the worse that association. So if you have really mild psoriasis, your increased risk of cardiovascular disease is probably really small.

Also, treating your psoriasis appropriately, perhaps with some of these new medicines that I mentioned, also reduces that risk. So make sure you get plugged in to a dermatologist or somebody else comfortable treating psoriasis.

People with psoriasis also get an increased risk of arthritis. There's a particular type of arthritis called psoriatic arthritis. So if you or somebody you know has psoriasis and get new joint pains, especially if you don't think they're sort of normal for your level of activity, especially if they're worse in the morning and associated with stiffness, definitely want to tell somebody about that.

Dr. Tarbox: And also, patients who have psoriasis are at a greater risk for both anxiety and depression, which is completely understandable given the fact that there can be some social isolation caused by people misunderstanding the condition or by a person's concern about being perceived differently when they go in public. So we do want to always screen our patients that have psoriasis for depression or anxiety.

And if that's a part of your condition that's affecting your life, definitely bring it up with your physician, because treating those mood disorders can help improve your overall state of health and then make the condition easier to manage.

Dr. Johnson: Unfortunately, there are a number of other health conditions that are also associated with psoriasis. I think the ones we mentioned are the most important, but I like to think that this emphasizes the importance of getting plugged in to good medical care and knowing that we have a lot of really great treatments for psoriasis these days.

Dr. Tarbox: Well, we want to thank you guys so much for listening today and learning more about psoriasis. Luke, I think you have some special thanks.

Dr. Johnson: Of course. I always have special thanks for the University of Utah for supporting the podcast and to Texas Tech for lending us Michelle.

You can find all of our "Skincast" episodes on Apple Podcasts or wherever you get them. And you can also find all of our other podcast, which is called "Dermasphere." Michelle, you want to talk to them about "Dermasphere"?

Dr. Tarbox: For sure. "Dermasphere," as we put it, is the podcast for dermatologists by dermatologists and for the dermatologically curious. It's about an hour long or so. It's longer than our "Skincast" episodes. And we discuss in more depth some of the conditions that we treat as dermatologists, some of the upcoming evidence and new treatments for different kinds of conditions, as well as some of the new technologies that will help us take better care of our patients.

Dr. Johnson: So if you like to nerd out about dermatology like we do, come check us out there. Otherwise, we'll see you next time right here on "Skincast."

Dr. Tarbox: Hello and welcome to "Skincast," the podcast for people who want to learn how to take the very best care of the skin they're in. I'm Dr. Michelle Tarbox, a dermatologist and dermatopathologist at Texas Tech University Health Sciences Center in beautiful sunny Lubbock, Texas. And joining me is . . .

Dr. Johnson: Hey, everybody. This is Dr. Luke Johnson. I'm a pediatric dermatologist and a general dermatologist with the University of Utah in Salt Lake City.

Dr. Tarbox: So today we're going to talk about something you hopefully don't run into personally, poison ivy.

Dr. Johnson: That's right. Poison Ivy is the alter ego taken by Dr. Pamela Lillian Isley, an eco terrorist and prominent enemy of Batman who first appeared in Batman #181. Just kidding. This is a dermatology podcast, so we're going to talk about the plant.

Dr. Tarbox: But great nerd culture. I'm proud of you.

Dr. Johnson: Thanks. So the rash that you get from poison ivy is technically allergic contact dermatitis, or ACD. You can get allergic contact dermatitis to all kinds of stuff. Think of something, you can get allergic contact dermatitis to that thing. But today, we're just going to talk about the plant types of allergic contact dermatitis: poison ivy, poison oak, and poison sumac.

Dr. Tarbox: So the poison plants all have the ability to produce a significant rash in humans upon contact. The first one we're talking about, of course, is poison ivy, because it's sort of the leader of the pack, if you will, of the itchy gang.

So Toxicodendron is its actual name. It's such a nasty plant it has toxic right there in the title. This plant is found everywhere in the United States, except for Alaska and Hawaii. Even in places where it was less common, it's starting to have territory expansions.

And it can really be just about anywhere, because it sometimes gets accidentally shipped with nursery plants around the base of a tree or shrub that's taken from one part of the country to be grown in another part of the country. So you can actually run into it pretty well in most places. Do they have it in Utah, Luke?

Dr. Johnson: They do. It shows up just about everywhere in Utah. How about in Texas?

Dr. Tarbox: Not as much in the part where I live because it's very dry and that plant likes a lot of moisture. But when we have our wet years, we end up with some expansions of the growth of those things out from around the bases of the nursery plants. And it's out in the countryside most places in the country.

Dr. Johnson: "Leaves of three, let it be." That's the saying, because this plant has what they call compound leaves with three leaflets. So a little plant stem will actually have three little leaves coming out of it, and the middle leaf is kind of longer than the others.

When I was learning dermatology, I remember complaining that, "Man, I'm already a doctor, and now they want me to be a botanist? And I'm also supposed to learn about bugs and be an entomologist and all that stuff?"

There are pictures of these plants. We can talk about what they look like. The edges of the leaves can be smooth or toothed. The surface can be glossy or dull. But I discovered that there are now apps that can identify plants. So instead of trying to memorize pictures or torturing our dermatology residents, we should probably just use these apps.

So some that I found are PlantSnap, Leafsnap, and Planta. So if you're going to go out hiking or camping, especially if it's somewhere kind of new for you, you might want to download one of those apps first and make sure that your children aren't tromping around at a big poison ivy patch.

Dr. Tarbox: I like that plan. One of the things that we kind of can unify with these plants is that they all have an oil that they make that is the problem child, the thing that causes the rash. And so that makes the rashes look a little kind of shiny or glossy, a lot of the time but not all of the time.

Dr. Johnson: They only produce this stuff at certain times of the year, certain seasons, or when the plants are doing whatever plant things they do. But sometimes these little black dots show up and that's the urushiol.

Poison oak and poison sumac also exist and are kind of similar. Poison oak is found in western North America and the Southeastern US. It's not a tree, despite the fact that oak is in the name. That was surprising to me. It's more like a shrub or a vine. And it kind of similarly to poison ivy has the three leaflets, and in the spring it has white flowers. So if you find something in the spring that has red flowers, you're probably good.

Dr. Tarbox: Yeah, white flowers, that could be a problem. Could you imagine if somebody made a bouquet out of those and then just . . .? Their poor little hands.

Poison sumac is also a thing. Less common. It is a shrub or a small tree up to about 30 feet and it tends to grow in wooded swampy areas like Florida in the southeastern portion of the United States. It's also present in wet, wooded areas in the Northern United States. So you and I probably don't have a lot of sumac in our areas, Luke.

Dr. Johnson: I don't think so. So they're easy to avoid, which is what you should do for all of these if you can. Just don't come into contact with them. Stay in your house, play video games, everybody will be fine. Well, probably not. Actually, there are some dermatologic conditions that can be associated with excessive video game playing.

So if you do come into contact with a plant, well, you want to wash the affected area. Not necessarily with just normal soap either. You want to use laundry soap, dish detergent, rubbing alcohol, and rinse. You want to get that plant juices out of anywhere that it could have gone, so rinse onto your nails. And remember, it could have gotten on your clothes, so carefully remove your clothes, perhaps with gloves or something, and put them in the wash.

Dr. Tarbox: And you want to wash your whole body surface because we may touch parts of our body with our hands that made contact with oil and transfer it. So one almost emergency situation that more commonly affects men is when they have contact with the plant and then maybe they go to the bathroom. And you can imagine that the severe allergic contact dermatitis on that part of your body might be significantly uncomfortable.

There are products that are made specifically to help you to remove the oil that causes the rash. One of the most common ones you can find is called Ivy Block. Again, we have no relationship with any commercial product. We just like people to be able to find the product in the stores.

So the active ingredient in Ivy Block is something called bentoquatam, and it tends to protect the skin like a shield against the poison ivy, poison sumac, poison oak by kind of blocking skin contact with their resin. They also make a soap that can help you to rinse off the oil very well.

Any of these preventative products, of course, you wouldn't want to get in your eyes. You obviously don't want to get poison ivy residue in your eyes either.

And one very important thing is to not try to go all vengeance on the plant and burn it. I've had several patients who actually, after they determined what had caused their rash was poison ivy, then sort of in retribution ripped the plant out of the ground and burned it. The problem is if you burn it, then you aerosolize the oil and you can actually give yourself a chemical pneumonitis. You can give yourself poison ivy in your lungs if you burn this stuff, so you should never burn it.

If you think you've been exposed to airborne, poison ivy resin from burning that kind of thing, you may need to seek medical care. So do not burn anything you think is poison ivy.

Dr. Johnson: "Leaves of three, let it be." Do not incinerate.

Dr. Tarbox: Now what about the rash, Luke? Does everyone who touches poison ivy get a rash?

Dr. Johnson: Interestingly, no. Maybe only about half of people seem to actually get this allergic contact dermatitis to poison ivy. And like other allergies, if you've already been exposed in the past, that means your immune system is extra ticked off if it sees it again. So if you've had a poison ivy rash in the past, and you get exposed to poison ivy again, you'll probably get a rash within a few hours of touching the plant.

However, if you've never seen poison ivy before . . . well, if you have not ever touched poison ivy before, and you end up touching it, then the rash might take a couple of weeks to show up. So remember how you were hiking in the woods two weeks ago? Do you have a rash now? Maybe it was poison ivy.

And it occurs where the leaves brush against the skin. So sometimes dermatologists refer to something looking like an "outside job." So if we're having an immune reaction within our body against something that's going on in our body, not a reaction to something outside our body, it usually doesn't show up as nice lines or swirls or curves and things like that. So if it looks like someplace where a leaf may have brushed and left a rash there, well, it could have been something like this.

Dr. Tarbox: So what do you say we should do if patients get this? How do we take care of it?

Dr. Johnson: Well, if it's not too bad, you can just treat it with over-the-counter stuff like soothing lotions and things and mild steroid creams and steroid ointments like hydrocortisone. A dermatologist or another doctor can prescribe you stronger medicines if necessary.

For really bad poison ivy, especially these people who burn poison ivy, we can sometimes even do steroids by mouth to help get over the reaction because it can be really, really horrible and it can last two or three weeks.

Dr. Tarbox: It can be quite awful. So the really best thing to do is just avoid it. If you, of course, know what the plant looks like, that helps. I encourage people to kind of refresh their memory about what these plants look like before they go on a hiking or camping trip.

You can also wear clothing that will protect the skin from both the sun and from the brush of those leaves. So a lot of sun-protective clothing with long sleeves or long pant legs can be preventative in terms of preventing skin contact. And then you can wear the Ivy Block when you're out and about in areas where the plant might live.

Dr. Johnson: The rash can blister, by the way. So if you see that you've got a blistering rash, it still could be poison ivy.

That's most of the poison ivy/oak/sumac stuff I wanted to talk about. I want to talk about Mr. Freeze next.

Dr. Tarbox: Okay.

Dr. Johnson: Thanks. Was waiting for that.

You can get allergic contact dermatitis to other types of plants as well. Compositae is a super common type of plant that causes allergic contact dermatitis. It doesn't cause it in nearly as many people as poison ivy does, which I guess is why it's not called poison sunflowers. They're just called sunflowers. But there are all kinds of plants in this family, sunflowers and things that kind of look like sunflowers with that kind of circle/radiate/Starburst appearance. It's a common thing we see in dermatology. Tulips can do it too.

Dr. Tarbox: Alstroemeria.

Dr. Johnson: What's that?

Dr. Tarbox: Alstroemeria. So there's a kind of Peruvian Lily that is used very frequently in floral bouquets because it's a hardy plant, and it lasts for a long time and has really beautiful blooms. So the Peruvian Lily or Alstroemeria can also cause contact dermatitis.

Dr. Johnson: So we like plants, but they might not always be your friends. In addition to allergic contact dermatitis, there's also irritant contact dermatitis. So the difference is that to have allergic contact dermatitis, your particular immune system has to be angry for some reason, whereas in irritant contact dermatitis you're coming into contact with something that is just irritating to human skin. A chemical burn is a good example of an irritant contact dermatitis.

And some plants can do it too, including plants that we eat, like garlic. So sometimes especially people who prepare a lot of food with these plants can start to get irritation of their fingertips, for example.

And also, there's this funny condition that some plants can cause called phytophotodermatitis. It's one of my favorites. There are particular plants that have a chemical in their juices and when the juice gets on the skin and then sunlight shines on the juice, you get this big reaction and it can kind of look almost similar to poison ivy. And its significant forms can be this itchy blistery rash. That calms down pretty quickly, but then you're left with this pink-brown discoloration that can last for like two years.

So common plants that can do that are citrus plants like limes. So some people refer to margarita hands. If you were on vacation in Mexico smashing limes for margaritas, you were probably hanging out in the sun too and bam, margarita hands.

There are also different weeds and things, like hogweed, that can do it. So sometimes we'll see this in people who are doing yard work or something.

Dr. Tarbox: And there are also plants that cross-react with a person's allergy to poison ivy. So for some people, it'll be mango peel. If you have a significant poison ivy response, then making significant contact with the peel of a mango fruit can potentially cause you allergic contact dermatitis.

So if you're one of those people who likes to get every last bit of mango out of the mango slice, and your skin is coming in contact with that mango peel, if you've had a reaction to poison ivy in the past, you may get a rash from that. So it's probably safer to just cut the peel off.

Patients can also react to ginkgo leaves or potentially cashew plants if they've reacted previously to poison ivy.

Dr. Johnson: That's all for today. Thanks for hanging out with us, guys. And thanks to our institutions. Thanks to the University of Utah for supporting the podcast, and thanks to Texas Tech for lending us Michelle.

If you like to nerd out about dermatology, you might be interested in our other podcast as well. It's called "Dermasphere." We say it is the podcast by dermatologists for dermatologists and for the dermatologically curious. We talk about dermatosis you can get from video game playing, for example. And I think we've even talked about Super Villains at one point, like they're depicted as having less hair than heroes. So we talk about some fun stuff. You can find that in Apple Podcasts or wherever you get your podcasts.

"Skincast" episodes you can also find on Apple Podcasts or wherever you get your podcasts, and, in two weeks, right in your earbuds. We'll see you then.

Parents will often bring their kids in to see me for skin issues, and I also get a lot of phone calls about rashes. Well, the hard part is I can't see your child's rash over the phone. Rashes are one of those things that your pediatrician will need to see in person or through a video visit in order to determine what the cause of the rash is and what to do about it.

Babies and diaper rashes are one very common concern. Babies get diaper rashes very easily, even within days of being born, because their skin is super sensitive. In fact, their skin is not fully developed until about 6 months old, which is why we say no sunscreen or bug spray until then.

Babies are also in diapers and they pee and poop a lot. Diaper rashes are basically contact skin issues due to the diaper fibers and due to the normal body chemicals and bacteria in the urine and stool.

Some babies are okay with just having diaper rash cream put on their bums. Others get more like burns. We used to even make our own diaper rash cream for our older son. His skin was so sensitive we joked that he would get a diaper rash if we looked at him wrong. We ended up using burn cream mixed with zinc oxide for him.

Parents often ask which diaper cream I recommend. My answer? Whichever works for your baby. I don't have a personal preference, and some creams work better for some babies than others.

If the diaper rash is red and bumpy, though, that's a yeast diaper rash. It's more in the front of the diaper area and less on their bottoms. Any over-the-counter yeast cream can help with that.

Then there are dry skin issues. Every winter, I have parents bringing their children to me for an all-over body rash that can be itchy. That's often either just dry skin dermatitis or eczema. For both, start with a cream that says "dry sensitive skin." And you can try mixing a little over-the-counter hydrocortisone with it and apply it twice a day for a few days.

Some kids with really bad eczema end up needing prescription creams, and that's when a trip to your pediatrician is needed.

There are all sorts of rashes. Most are viral, some are bacteria, but for all other rashes, it's best to have your child seen so we can check it out and see what treatment is needed.

Viral rashes need no treatment. They'll go away on their own. Bacterial ones sometimes just need topical antibiotics, but sometimes need a prescription for oral antibiotics.

If you have a concern about your child's skin, go ahead and bring your child in to see their pediatrician. Chances are we've seen your child's rash before and are able to help.

Dr. Tarbox: Hello, and welcome to "Skincast," the podcast for people who want to learn how to take the very best care of the skin they're in. This is Michelle Tarbox. I'm an associate professor of dermatology and dermatopathology at Texas Tech University Health Sciences Center in beautiful sunny Lubbock, Texas. And joining me is . . .

Dr. Johnson: Hello. This is Dr. Luke Johnson. I am a pediatric dermatologist and a general dermatologist with the University of Utah.

Dr. Tarbox: Today, we're going to talk about atopic dermatitis, more commonly known as eczema. Luke, as a pediatric dermatologist, I know you see a lot of patients with this condition, so what is it?

Dr. Johnson: I sure do. It's an itchy red rash, and it's common. There are a lot of things in the world of dermatology that could be described as itchy red rashes, so there are a few things about eczema that look distinct to a skin doctor, but maybe not so much if you don't spend all your days looking and thinking about skin.

It tends to be scaly. It tends to be what we call ill-defined, so it's kind of hard to tell where the rash necessarily starts and stops. It tends to show up in specific areas of the body, and those are a little bit different depending on how old you are, but it's especially common in babies and little kids. There are some medical data that says about one in five babies can get it. And then it's common in other age groups as well.

Dr. Tarbox: Yeah, the literature is about 15% to 20% of kids can have atopic dermatitis. The words eczema and atopic actually are kind of fun. So eczema comes from a Greek word ekzein, which is to boil over or breakout, and atopic means out of place. But really, it's just this eruptive, pruritic rash, this itchy rash, that little kids can get, and it can be so disruptive to their little lives, and as well to the family.

So what causes it, Luke?

Dr. Johnson: Well, what I sometimes tell the families who come in to see me is that if you look in a dermatology textbook about what causes eczema, you find a huge list of things. And you just told me that you wrote a chapter in a textbook about what causes atopic dermatitis. So not only is there a huge list of things, there's an entire chapter about it.

But I tell people that, in my opinion, the most important thing is that can cause it is that the skin is leaky. So one of the most important functions of the skin is to be a barrier between your insides and the outside. And in people with eczema, it's leaky, so it's not as good a barrier. And because it's leaky, water can evaporate away. So people with eczema tend to get dry skin, and then other stuff can get in through those leaks that's irritating and creates the itchy red rash that we see as eczema.

Dr. Tarbox: I love that explanation, Luke. And I think that that's such a nice way to encapsulate it for families. We know from looking at the science that it's caused, in some patients, by a mutation in a gene that helps make the outside of our skin more waterproof. If we lose that waterproofing and we do have leaky skin, we have to remember that water always flows downhill, even microscopically. There's more water in our skin than there is in the surrounding air, and so we lose water through our skin to the air and then other things get in.

Things that can make that worse are an even more dehydrated internal air environment, like what happens in the wintertime when we turn on the heaters and the air becomes dehydrated, as well as a contaminated environment with lots of particulate dust.

Dr. Johnson: And I sometimes have people say, "Well, why does my child have this leaky skin whereas other people don't?" And the unsatisfying answer that I give to a lot of people who have questions about why this happened to them is, "Well, mostly it's bad luck." But what it probably is, is a combination of genes and probably some other factors as well that just came together in this particular configuration, sadly in your child, so that he or she has eczema.

It's not a traditional genetic disorder, so it's not like, "Oh, my dad has it and my grandpa has it. Now I have it." It's more like there is a combination of genes, and if somebody in particular happens to get the right combination, then they are more prone to this kind of issue.

Dr. Tarbox: We also find that some things that mess up what we call our skin barrier, that waterproofing of the outside of our skin, can make eczema worse. Harsh detergents can do this either in clothing or in the products that we use to cleanse skin. Sometimes things that we apply in an effort to improve the eczema can cause problems if it's got irritating chemicals or things that we're allergic to in them.

And then we also wonder about immune dysregulation. Have you seen some flares of eczema in kiddos that have had to deal with the COVID virus?

Dr. Johnson: I don't know about the COVID virus in particular, but it's pretty well known that if kids get a cold, just like an upper respiratory tract infection, their eczema tends to get worse for sure.

Dr. Tarbox: The immune system plays a role. The environment plays a role. And then patients' contact with any kind of chemicals or anything that makes an irritation to the skin also plays a role.

Dr. Johnson: There are other skin diseases that can sometimes be mistaken for eczema: psoriasis and, of course, there are lots of others as well. So I admit I did not know what psoriasis was until I went to medical school. I kept getting it confused with cirrhosis, which sounds the same, but it's completely different. That's a liver disease. And so sometimes I have patients who come in and tell me they have psoriasis and, actually, they have eczema.

It's also not an allergy. So I feel like I have lots of patients and parents who feel that their eczema or their child's eczema represents an allergy to something. And it's true that kids with eczema have more allergies than kids without eczema, but the eczema itself is not an allergy.

Dr. Tarbox: And some of you may know that Mr. Dr. Tarbox is an allergist, so we spend a lot of time talking about this particular interplay of different kinds of medical conditions. When we're talking about a rash from food allergy, that's usually something that makes hives. Some people call them welts. Sometimes we call it urticaria. This is a different kind of rash than eczema is. It's more come-and-go very quickly type of rash than eczema is. So foods can cause a rash but not specifically eczema. What about . . .

Dr. Johnson: There's been a lot of research into food and eczema. So I find that it's pretty common for parents to wonder if it's something about the diet that affects the child's eczema. And again, there's been a lot of research and the general answer is no, there's nothing about the diet that affects their eczema, which I know in some ways is kind of disappointing because we can control our diet.

And I think one reason that there are a lot of people who really want the diet to play a role is because eczema is by its nature uncontrollable. It comes and goes, sometimes for a good reason, like it's dry in the wintertime, and sometimes for no good reason, it's just there. And there's a tendency to want to say, "Oh, well, it's because of something I did," like feed him peanuts yesterday, or whatever. But really, it was just a coincidence.

And while we can control our diet and it doesn't help, we can control what we put on the skin, the sorts of soaps and stuff we use, and other things that we'll discuss. But I do want to reassure people that in the vast majority of cases, the child's diet or the breastfeeding mother's diet is not related to the eczema.

Dr. Tarbox: Now, one thing parents can be in control of that can influence the severity of eczema is cigarette smoking in the house, especially because the particulate debris that can come out from smoking and the contaminants that can end up in the clothing fibers and on the carpet and on the child's skin have been proven to potentially exacerbate eczema.

So if you do have a child with eczema, trying not to smoke around them and trying to keep any clothing contaminated with cigarette smoke away from them could be beneficial.

Dr. Johnson: Eczema is also not anyone's fault. It's not because of something that you did or didn't do during pregnancy, or something that you did or didn't do while taking care of your baby. There are things that can make it worse, like smoking, and there are things that can make it better, like moisturizing the skin. But to current medical knowledge, there's really nothing you could have done to have prevented this.

Dr. Tarbox: So, Luke, when a parent comes to you with a small child that has eczema and they're looking at you with that look of desperation in their eyes, that question that's unasked, "Is it always going to be this hard to take care of this kid's skin?" what do you tell them?

Dr. Johnson: It's definitely a lot of work. And when I have a child with bad eczema and then they're better at follow-up, I make sure to tell the parents a lot of the reason that they are better is because of your hard work. It's definitely hard work.

The good news is that about 50% of kids outgrow it at some point. The earliest that tends to happen is around age 2, though for most patients, it's more like middle school age, so maybe age sort of 10 to 12 they start to outgrow it.

And the genes don't change. So what is it that changes that makes some people outgrow it? Well, we're still sorting that out as doctors. We don't really know. But because the genes haven't changed, if you were prone to eczema as a kid, there's probably something about you that's still prone to it even later in life.

So it's not uncommon that I have an adult patient come in or a teenager and it looks like they have eczema and they say, "Well, yeah, I think I had eczema when I was 3, but I haven't had it for 20 years. What's the deal now?" And to them, I say, "I'm sorry, I don't have an answer as to why this suddenly came back, but it is something that we see."

Dr. Tarbox: One reason we think that kids outgrow eczema is that there's this compound that gets formed in the outside layer of the skin that's appropriately named natural moisturizing factor. And small children don't form it well in all areas of their skin, specifically the areas where they tend to get bad eczema like their cheeks. So it takes them a while to start forming that uniformly over their skin.

And it's formed from that same gene that sometimes gets messed up in patients that have atopic dermatitis or eczema, which is called filaggrin. And whenever this is present, it improves the health and quality of the skin. So researchers are actually looking at replacing it synthetically to try and help improve the skin in patients that have atopic dermatitis.

Dr. Johnson: Finally, I want to point out that we cannot diagnose eczema with any kind of test. The good news is we generally don't need to. Eczema generally looks pretty obvious to most skin doctors and probably a lot of pediatricians and other sorts of doctors as well. So we don't need testing to diagnose it.

You can take a biopsy of the skin where you cut out a little piece and look at it under the microscope. That's not necessary in the vast majority of cases because, usually, eczema looks like eczema and we can figure it out.

But just like the fact that it's not an allergy, we can't do allergy testing, for example, to sort out eczema or to figure out whether or not your child has eczema.

So the best test is to have a doctor look at you or look at your child and listen to the history and figure out if it looks and sounds like eczema.

Dr. Tarbox: One of the good things too is that we know more about it now than we have ever before in history and we have more therapeutic options than we did previously.

So on our next episode of "Skincast," we're going to discuss ways to help treat patients that have atopic dermatitis or eczema.

Dr. Johnson: Stay tuned for that, and thanks so much for hanging out with us today, guys. And thanks to the University of Utah for supporting the podcast, and to Texas Tech for lending us Michelle.

If you are a super dermatology nerd, you might be interested to know that Michelle and I have another podcast. It is called "Dermasphere." It's really intended for other dermatologists and people practicing dermatology, but again, if you're a super dermatology nerd, maybe you'll find it fun as well.

We'll see you guys next time.