JUST THE BASICS

Hives (also called urticaria) are itchy bumps that many people associate with having an allergic reaction. But did you know that some people can get hives even if they don’t have any allergies? “Physical urticarias” are hives triggered by skin irritation, no allergen needed. Examples from the cartoon include heat against the skin, cold against the skin, and pressure on the skin. Some people can even be triggered by UV radiation (sun) and water!

TELL ME SOMETHING NERDY

Dermographism, which means “to write on the skin”, is a form of physical urticaria in which light pressure against the skin can lead to the formation of welts/urticaria. Some people with dermographism report their symptoms are worse after eating, raising concern for a food allergy. However, an interesting study found that food allergies would not explain this phenomenon. While more studies are needed, they speculated that changes in blood flow, parasympathetic tone, or serum osmolality after eating may lower the threshold needed to trigger dermographism in some patients.

To be published in the October 2024 Annals of Allergy, Asthma & Immunology  

Study referenced above: Yücel MB, Ertas R, Türk M, Muñoz M, Atasoy M, Maurer M. Food-dependent and food-exacerbated symptomatic dermographism: New variants of symptomatic dermographism. J Allergy Clin Immunol. 2022 Feb; 149 (2):788-790.