food allergy topical

Currently, there are no topical preparations proven by evidence-based medicine that can solve the root cause of food allergy. All topical products can only temporarily relieve local skin redness, swelling, and itching caused by food allergy. They cannot act on the activated systemic immune response. When severe food allergy occurs, only external application of drugs will 100% delay the opportunity for treatment.

I was doing follow-up consultation in the allergy department a while ago, and I met a mother who brought her 6-year-old baby. After the baby ate half a mango, the area around her mouth became swollen, and a series of small blisters appeared. After asking, I found out that my grandma noticed that the baby's lips were red, so she directly applied two layers of the strong glucocorticoid ointment that she used to treat eczema at home. The area that was just itchy at first turned into a fever after two hours, and the baby scratched her skin. In fact, this is not the only one. I have seen too many people treat skin symptoms caused by food allergies as ordinary rashes, and then apply various things on them. They even think that "medicines are only three parts poisonous, and taking medicine is not as safe as applying medicine." This cognitive bias has really fooled many people.

At present, the industry's attitude towards topical food allergy is actually divided into two groups. There is no right or wrong, but the applicable scenarios are very different:

The mainstream view of Western medicine allergology departments is that most food allergies are IgE-mediated systemic immune reactions. The skin rashes and redness and swelling around the mouth you see are just manifestations of immune complexes deposited in the skin and mucous membranes. The allergic cascade reaction in the body has already started. Externally applied things can only penetrate the skin to the epidermis at most, and cannot touch allergens and inflammatory factors that have entered the blood circulation, so it is impossible to cure allergies. The only exception is a simple food contact allergy - for example, if mango juice touches the mouth or pineapple juice rubs on the hands, and there is no rash all over the body, respiratory tract congestion, abdominal pain and diarrhea, then promptly wipe off the food residue on the skin surface and apply a little weak glucocorticoid ointment (such as desonide cream) or calamine lotion, which can indeed quickly relieve local discomfort and will not have any side effects.

There is also an empirical solution supported by many naturopathic and traditional medicine practitioners, such as pounding fresh purslane and applying it externally to relieve allergic redness and swelling, or using herbal ointment without additives to relieve itching. I will not directly deny this kind of solution. After all, I have met several patients who said that they have used it and it is indeed useful, but I must be reminded that: This type of program is not supported by large-scale clinical data, and individual differences are huge. Moreover, many people are allergic to herbal ingredients and fresh plant juices, which may aggravate local irritation. It is best to test the sensitivity behind the ears before using it. If you feel no discomfort after applying it for 15 minutes, then use it on the affected area. And as long as systemic symptoms appear, stop taking the medicine immediately.

Many merchants are now touting "purely natural food allergy external medicines" and "just apply them without taking medicine". They are simply charging an IQ tax. Last year, a girl in her early 20s came for a follow-up visit and said that she had been allergic to shrimp before. After eating it for the first time, she only developed hives all over her body. She bought an "anti-allergic herbal ointment" sold online and applied it. At that time, her allergy symptoms were mild, and it didn't take long for it to disappear. She thought this ointment was really useful. As a result, the second time she ate half a plate of braised prawns, she not only broke out in rashes all over her body, but also felt that her throat was tight and she couldn't breathe. She even sat there and applied ointment on her neck. If her roommate hadn't called 120 for her at home, something serious might have happened.

When I usually provide science education to patients, I always tell them that topical products always come last in the priority list of treating food allergies. If you really encounter a food allergy, you should do three things first: Stop eating the suspicious food immediately, and wipe off any residue around your mouth and hands. ； Second, count your breathing, feel your heartbeat, and see if you are out of breath, flustered, or have stomachache. If you feel any, don’t hesitate to call 120 immediately. ； If there is only a little local redness and itching but no other discomfort, then consider whether to apply something to relieve it. Also, you should check the ingredients before applying. Do not put Internet celebrity essences and aloe vera gel that contain alcohol, fragrance, and strong preservatives on the allergic area. They are purely for irritation.

Oh, by the way, there are also some topical immunomodulators under development that specifically target the symptoms of atopic dermatitis caused by food allergies. However, they are still in phase III clinical trials and have not yet been launched on the market. All the topical products available on the market that claim to be "specialized in treating food allergies" are basically just ordinary soothing creams with some publicity gimmicks. Don't take them seriously. To put it bluntly, the core principle of treating food allergies is to avoid food allergens + take or inject anti-allergic drugs when necessary. Topical use is just an icing on the cake. Don’t reverse the priorities.