Transcription
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 and 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: Hey, everybody. My name is Dr. Luke Johnson. I'm a pediatric dermatologist and a general dermatologist with the University of Utah.
Dr. Tarbox: So today we're going to talk about urticaria sometimes also referred to as hives or welts. Luke, what's urticaria?
Dr. Johnson: Well, urticaria is hives. Medical term for hives is urticaria. I have also heard people refer to them as welts or welps sometimes, but I think most people call them hives. And there's a type of white blood cell called a mast cell that is responsible for these things showing up on your skin.
Mast cells are all full of histamine and stuff like histamine, and various things can cause them to basically explode and release their innards all over and those innards contain histamine and some other stuff. And that causes the blood vessels to get swollen, which causes the skin to get swollen in that area, which is why hives are pink and sort of raised up.
Dr. Tarbox: And what kind of things can cause hives, Luke?
Dr. Johnson: Many things can. In children, the most common cause is just a viral infection. Usually, something mild like a cold. So if you have a child and they get a bunch of hives, you don't need to get too excited. The most likely explanation is that they have a viral infection, especially if they have some kind of other symptom like if they have a runny nose or a cough or something like that, it's probably what's going on.
Sometimes the hives can be the only thing that the kids have, even if they also have a virus. They're just otherwise healthy but have some hives, it's related to their immune system, getting extra excited about what's going on not necessarily to the virus specifically, and just tends to go away on its own.
Another common cause of hives is medications. Again, the immune system sometimes gets excited about things that it doesn't necessarily need to get excited about, and medications are the most common cause of hives in adults probably because they take more medications and their immune systems are a little bit more mature and a little bit more used to the viruses that can cause the hives in kids, but kids can also get hives from medications and adults can also get hives from viruses though it's a lot less common.
Dr. Tarbox: Some of the most common medications that can cause hives include penicillin, aspirin, ibuprofen, naproxen, and blood pressure medications.
Dr. Johnson: There's also a large category of hives that end up being idiopathic.
Dr. Tarbox: Wah wah.
Dr. Johnson: And idiopathic is the medical term for, we don't know why. And we made up a term idiopathic so that we didn't sound by saying, well, we don't know why.
Dr. Tarbox: We say we say idiopathic, so we don't sound like idiots.
Dr. Johnson: Right. But the good news is that even though we can't always figure out what's causing the hives, we can usually treat them safely and effectively. We can talk about that later.
Dr. Tarbox: There's also some other small categories of hives. Some people will get them related to hormonal changes. Women will sometimes get them in pregnancy, things that kind of perturb the immune system in one way or another can create hives. Some people even get at hives from sunlight.
Dr. Johnson: It's true, very rare. And of course, allergies can cause hives. I'm sure there are people out there who've gotten hives after they've been exposed to a dog or a cat or rolling around in the grass or something.
And then there's what we call physical urticaria. So there are various what we refer to as physical stimuli, things that happen to your skin that can cause it to develop a hive. So there are these very rare patients who can get highs from sunlight, some people get hives from vibration on their skin, some people get hives when their skin gets cold or when it gets wet. The most common of these physical urticarias is dermographism.
Dermographism literally means skin writing, and that's because when you scratch the skin, you create a hive and the exact line where you scratched. So if you were so inclined, you could scratch your name onto the back of somebody who has dermographism, and then your name would show up in hives.
Dr. Tarbox: Yeah. About 2% to 5% of the population has dermatographism, so if you don't personally have this unique human trick, you probably know somebody who does, who can really make a little billboard out of their back.
Dr. Johnson: And usually people aren't really bothered by it though sometimes they can be. And then sometimes people can get dermatographic even if they normally aren't if they have like a viral infection, for example. So the same things that can just caught as hives can also just make your mast cells extra twitchy and make you dermatographic.
There are other pretty rare causes of hives. Like there are some things that you can come into contact with, then you get a hive. That's pretty uncommon. We call that a contact urticaria. And then the ones that are kind of scary is that every so often, hives can mean that there's something a little bit more going on in your body. So sometimes people who have an autoimmune disease can get hives and sometimes certain infectious diseases can cause hives, but don't let your brain go there right away. If you've got hives or your kid has hives, it's most commonly a virus or a drug or it's idiopathic.
Dr. Tarbox: About 10% of the population will experience hives at some point in their life so it's relatively common. The good news is most of the time it goes away. About, you know, a small percentage of patients will have hives that last a little bit longer. When they last more than six weeks, we call that chronic urticaria and then we start getting more serious about trying to figure out exactly what's causing the problem. But what can people do about their hives, Luke?
Dr. Johnson: Well, hives are mostly caused by histamine, and the good news is we have medicines that are antihistamines. There's a lot of them and they're over the counter. There are some that are sedating, means they tend to make people sleepy. And then there are some that are not sedating, meaning they don't tend to make you sleepy. So generally, we recommend that you take a non-sedating antihistamine in the morning and a sedating one at night. Do you have some favorites, Michelle?
Dr. Tarbox: I do. My actual favorite one for hives is Allegra or fexofenadine. It comes in the 180-milligram dose over the counter. It's important that you don't need the decongestants. So you don't need an Allegra-D, Just plain Allegra is the medicine that I prefer the most for urticaria for the non-sedating antihistamines. For the sedating antihistamines, we have a couple of options that we can use.
Dr. Johnson: Benadryl's the most common example of a sedating antihistamine. The generic name is diphenhydramine. It's a fine choice for the evening, as long as it doesn't make you groggy in the morning. There's also a prescription version of Benadryl called hydroxyzine that you make have seen occasionally. Other non-sedating antihistamine, there's a lot of them. The brand names are things like Xyzal and Zyrtec. The generics are levocetirizine, and cetirizine, they're also all good choices.
Dr. Tarbox: Some patients can get a little bit sleepy with cetirizine and levocetirizine, more cetirizine which is Zyrtec. About 25% of the time, it actually crosses the blood-brain barrier and can cause some fatigue. So if you're one of those patients, you would choose a different non-sedating antihistamine to help aid things. So we talked about Benadryl as a sedating antihistamine being helpful for itch. What about topical Benadryl, Luke?
Dr. Johnson: Well, before we move on to topicals, Michelle, I want to just talk about what to do. If you're itchy, you take an Allegra or something in the morning, a Benadryl or something in the evening, and you still got these hives, well, you can increase the dose.
So we know that taking up to four times the normal daily doses of these antihistamines is safe and is usually what we do if people don't get better with kind of the normal dosing. So for example, you could take three Allegra fexofenadine throughout the day, and then a Benadryl diphenhydramine at night. And if that's still not controlling your hives and you're miserable, well, that would be a good time to reach out to us. Though as you say, there are topical options as well.
Dr. Tarbox: Yeah. So when we were talking about topical products and we talked about oral Benadryl for as a sedating antihistamine, we were going to say, what do you think about that topical Benadryl?
Dr. Johnson: I hate topical Benadryl.
Dr. Tarbox: Why do you hate it?
Dr. Johnson: Well, Benadryl's a brand, and so if it's topical diphenhydramine, which is the oral antihistamine. It doesn't work if you put it on your skin and strangely it can actually make you allergic to it. So don't use diphenhydramine cream. I think it's possible that the brand Benadryl also makes a hydrocortisone cream just to confuse things, and a hydrocortisone would be a good thing to put on your hives. It can help the inflammation calm down.
Dr. Tarbox: Yeah, I think that that would actually potentially be beneficial. So topical steroids like topical hydrocortisone or prescription topical steroids can sometimes be beneficial for itching. So do we need to get super excited about figuring out what's causing this?
Dr. Johnson: Usually not. And I know it's frustrating to not know what's causing the hives, but if they get better with antihistamine and then they just go away and don't come back, I am comfortable living in ignorance.
So if you've got hives for just a short period of time, like less than six weeks, that's what we consider short. And especially if the antihistamines control them and they go away, I don't think you need to knock yourself out trying to figure out what's going on.
But situations where you might want to try to figure out what's going on as the hives have been going on for a long time, like more than six weeks, especially if antihistamines are not sufficient to control them.
If you think it's obviously related to some kind of trigger, especially like a food, especially in like a little kid. So if somebody eats peanut butter and they get hives five minutes later, don't eat any more peanuts and you got to make sure you know exactly what's going on there because you can have these dangerous anaphylactic reactions to stuff like that.
But if you just have some hives and it's not obviously related to a food, most likely it's not the food that you ate last night or for breakfast or whatever.
If you have some other funny symptoms that are unexplained, like you've just been getting fevers for no reason, you feel crappy, you also have hives, we should figure that out. And if the hives are just miserable, you know, you've tried antihistamines, they're not better, you're itchy as heck, you're hating life, we should help.
Dr. Tarbox: I like it. So in terms of what doctor people should see to help them when they do get to that state where they're just miserable and they need some help, I actually feel particularly qualified to talk about this because both myself and my husband's specialties treat urticaria. So I am a dermatologist, my husband is the allergist, and both of us are capable of taking care of patients with urticaria.
We have a relatively similar toolkit, although we sometimes use it a little bit differently. If there's a suspicion that there is an inciting element like a pet or food, it might be more helpful to go see an allergist because they can do something called prick testing.
Prick testing allows us to test for the kind of allergy that can cause hives as well as the kind that causes sneezing. If you're having other symptoms that involve the skin, a dermatologist may be more able to help you. But the real answer is when you get urticaria, usually you get it quickly and usually you're pretty uncomfortable. So really whoever you can get in with first is probably the one that you would choose so that they can get you on the road to recovery.
Dr. Johnson: Our first step is usually these antihistamines plus maybe some topical steroids, but if those aren't controlling your hives, know that there are powerful prescription medications out there that can help.
And I think that's all we've got time for. So thanks for hanging out with us today, guys. 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 would like to hear more of Michelle and I talking, you can listen to our other podcast.
Dr. Tarbox: Our other podcast is called "Dermasphere." That podcast's a bit longer. It's about an hour-long and it's actually aimed at people who take care of the skin. So we call it the dermatology podcast by dermatologists for dermatologists and the dermatologically curious. We invite anyone to come listen though. If you want to learn more about the science behind skin, it's a place that you can take a deep dive.
Dr. Johnson: Thanks for hanging out and feeling hiver with us today. We'll see you guys next time.