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Answering Patients Questions on Urticaria and AD: Q&A With Dr Lio

Atopic dermatitis (AD) and urticaria are common skin conditions. The estimated prevalence of atopic dermatitis is 12.98% in children and about 7.3% to 10.2% in adults.1 The lifetime prevalence of urticaria is estimated to be about 20%, while chronic urticaria has an estimated lifetime prevalence of 0.5% to 5%.2 Acute urticaria is generally easier to manage and does not always require a visit to the dermatologist, but chronic spontaneous urticaria can be far more difficult to treat and leave both patients and dermatologists feeling frustrated.

“We are learning so much more about the immune system and we have increasing numbers of new therapies—there is tremendous hope in our pipeline for giving relief to so many who have not yet had it,” said Peter Lio, MD, clinical assistant professor of dermatology and pediatrics at Feinberg School of Medicine, in an interview with The Dermatologist.

While these therapies are being developed and studied, many patients are still burdened with these diseases and are looking for ways to improve their conditions quickly. They may present with questions regarding the possibility of managing their disease with food, how to tell if they have hives or eczema, among others. Dr Lio, MD, answers a few of these questions for patients with urticaria or AD.

Q1: Is it common to have hives and eczema?

Dr Lio: When we consider that both urticaria and AD are common allergic dermatoses, it is surprising perhaps, that it seems relatively rare for people to have both in my experience. The vast majority of urticaria patients I see are those with chronic spontaneous urticaria—a troubling and more chronic condition that usually does not have a clear trigger. These patients are usually otherwise quite healthy, although there are occasionally other auto-immune conditions associated with it, such as thyroid disease.

Many of my AD patients can certainly get acute urticaria from touching or eating certain things—allergies are much more common in our patients with AD—but because these are usually figured out relatively quickly, the vast majority are able to avoid those known triggers and seem to almost exclusively have eczema rather than hives.

Q2: How can I tell the difference between hives and eczema, especially if I or my child has severe disease?

Dr Lio: The lesions of hives and generally swollen, red itchy bumps that change rapidly. In fact, if you outline an individual hive, almost always the shape of that hive will have changed within a day. You might still have hives, but the individual spots come and go. This is very different than eczema where the patches and plaques tend to stay in place and be very stubborn. Unlike the smooth puffiness of a hive, eczema tends to be scaly, dry, and sometimes even open and oozing.

Q3: If I have hives or eczema, will I need patch testing?

Dr Lio: Patch testing is an important tool that helps us differentiate allergic contact dermatitis from eczema. Rarely, there are some contact allergens that can cause urticaria, but usually we’re looking for things that cause eczema. A good example of this that many people are familiar with is nickel dermatitis. This is an allergic contact dermatitis that causes and eczematous rash in the areas that touch metal. Commonly this is seen under the belly button from the snaps on jean or from the metal of a belt buckle but can also be seen from watch bands and jewelry, such as earrings. Once we know what is causing the allergic contact dermatitis through patch testing, we can remove these from the patient’s environment and watch them clear up. Unfortunately, some patients have both allergic contact dermatitis and AD so even if they avoid all the known allergens, they may still have skin problems.

Q3: Are there any foods that can trigger hives?

Dr Lio: There is a large literature around this tough question. First, true food allergies, such as those to peanut or milk or eggs, often do cause urticaria in allergic patients. Widespread, itchy hives can develop within minutes of eating such a food, and they can get worse than that even and develop angioedema (large areas of swelling, often on the face and lips) and even cause potentially life-threatening anaphylaxis. These are all part of a spectrum of type I hypersensitivity reactions that can happen from foods, medications, or really anything that people get allergic to. For them, we know that these foods will cause urticaria and they must be avoided.

For patients with no clear trigger or those with chronic spontaneous urticaria, there is some indication that a low-histamine diet can be occasionally helpful. There are also things called “pseudo-allergens” (not true allergens but these may trigger a reaction that resembles an allergy), and people will often avoid things like food additives and certain fruits, vegetables, and spices in a “pseudo-allergen elimination diet.” However, it’s not clear to me that this is very effective.

Q4: Does diet affect my AD?

Dr Lio: This is another big question for AD and we wrote a large review on it recently. The bottom line is that for most people with AD, diet is usually not the answer. I wish it were, because it is something we can control more easily. That said, eating a healthier diet is hard to argue against, and I think that there may be more general anti-inflammatory diets that really do show some benefit and I remain open to trying them.

The issue is that we are often recommending so many things for these patients that we hate to add more things for them to do. For children especially, big dietary changes can be very stressful and we know for certain that stress can contribute to flares, so we walk a very thin tightrope.

Q5: Do you recommend dietary changes if I have AD?

Dr Lio: I’m always wary of this in children because I have seen real, damaging malnutrition in kids with bad eczema that was done with the best intentions. Usually someone is suggesting cutting more and more foods in an effort to “find the trigger” and the kids sometimes begin to miss essential nutrients. This can be catastrophic for their growth and development. 

For adults, I’m much more open to experimentation so long as they are getting adequate nutrition and being honest with themselves. I’ve seen a lot of patients in my 15+ years of practice and the number one thing people say after a big dietary change is: “I thought it was a little bit better... but then I sort of fell off the diet.” Major diet changes, such as going 100% gluten and diary-free are hard--really hard! Most of us could not keep it up even if that were the whole answer. Sadly, I’ve had patients go gluten-free, dairy-free, and sugar-free, and basically eat an incredibly limited diet for months and say that exact thing: “Gosh, I was a little bit better...” 

Importantly, I don’t want patients to feel guilty about it. One thing about recommending a diet change is that it’s always easy to guilt someone by saying: “You need to do it longer, 3 months isn’t enough.” Or, worse, “You had a bit of soy sauce in February—the gluten in there ruined everything! You have start over and try harder!” 

Last point: a recent paper has shown that elimination diets have another negative aspect: avoiding foods that you are not truly allergic to can actually cause you to lose your tolerance to them! In other words, by avoiding eggs, you can actually become allergic to them, resulting in a real type-1 allergy, with hives, angioedema, or even anaphylaxis. Thus, it may not actually be a good idea to cut foods from the diet without a very good reason.

However, eating a healthy diet is so important! Eat whole foods, cut processed foods and sugary foods whenever possible, and eat mostly a plant-based diet. These seem to be key for good overall health and are still very doable for most patients. Unless there is a true allergy to a specific food, however, it might do more harm than good to cut it out of your diet—work with your allergist or dermatologist to come up with a good plan.


1. Silverberg JI. Public health burden and epidemiology of atopic dermatitis. Dermatol Clin. 2017;35(3):283-289. doi:10.1016/j.det.2017.02.002

2. Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol. 2014;133(5):1270-1277. doi:10.1016/j.jaci.2014.02.036



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