As strange as it sounds, being allergic to the cold is a real thing, and it’s called “cold urticaria.” Compared with nut or pollen allergies, an allergy to cold temperatures is much less common, affecting around 0.05% of the population, which is why you might not have heard of it before. However, like other allergies, people with cold urticaria will have a similar reaction. When the skin comes in contact with cold, be it a liquid, an object or air, it triggers a misguided immune response; histamine from mast cells is released, resulting in a breakout of red, itchy welts, or hives. And if the area of skin exposed is large enough, it is possible for the immune response to result in anaphylaxis, a potentially life-threatening condition.
Cold urticaria is diagnosed through a provocation test in which a patient’s skin is exposed over the course of 5 minutes to decreasing temperatures to determine a threshold temperature at which symptoms are triggered. This kind of test can be administered using a device called a TempTest, or even an ice cube. Once diagnosed, patients can avoid flare-ups by avoiding cold foods, drinks, and environments, and can also take antihistamines to reduce potential reactions.
While the immune response that happens in response to cold is understood, the reason why it happens is less clear. Cold allergies are commonly linked to other autoimmune disorders, but they can be completely idiopathic as well. In the search for an answer, a study by the National Institutes of Health (NIH) looked at a genetic analysis of 27 people with cold urticaria. The researchers found mutations in a gene, specifically phospholipase C-gamma2 (PLCG2), to be causally linked in all cases due to its role in the activation of immune cells. This suggests a genetic cause for cold urticaria and raises the possibility of potential molecular interventions to resolve the condition.
So, being allergic to the cold is more than your mind hating the dreadful Montreal winters — it can happen when your immune cells hate them too.
Cat Wang recently graduated from McGill University with a Bachelor of Science (BSc) degree in the anatomy and cell biology program and is currently deciding on a Master’s program.