Cold weather is an inconvenience for many, as it requires adding layers of clothing or increasing heating. But for some, exposure to cold can cause a severe and life-threatening allergic reaction.

Cold urticaria is a rare but potentially serious condition, as exposure to low temperatures leads to disruption of the immune system. Symptoms may include a rash, swelling, pain and, in some cases, life-threatening anaphylactic shock.

This condition was first described in 1792 by the German physician Johann Peter Frank. Today, it is approximately twice as common in women as it is in men, and the average age of onset is the early 20s, although it can affect people at any age.

The good news is that between 24% and 50% of people with this condition see improvement, or even complete remission, over time.

Symptoms of cold urticaria

There are two types of this case:

  • Primary cold urticaria is the most common, accounting for about 95% of cases, and its cause is often unknown.
  • The remaining percentage, 5%, is classified as secondary urticaria, associated with underlying diseases or infections, such as Epstein-Barr virus, certain types of lymphoma (blood cancer), HIV, and hepatitis C.

Primary cold urticaria usually causes a rash, swelling, bumps, or hives, although some people also report fatigue, fever, and joint pain.

Symptoms usually appear when the skin is exposed to cold, but may also appear when the skin temperature rises. Triggers are not limited to cold weather, but include swimming, eating frozen foods, drinking cold liquids, and touching cold objects.

The mystery of papyrus urticaria

With the exception of some very rare genetic causes, it is still unknown why some people develop primary cold urticaria, according to Study Finds.

Mast cells clearly play a role, as these cells act as primary warning cells in the body’s tissues, including the skin, alerting the immune system to signals of danger or germs.

The cause of mast cell activation in cold urticaria remains a mystery, although one theory suggests that exposure to cold prompts the body to produce so-called autoallergens, which are substances that stimulate an immune response against the body’s own tissues. More research is still needed to understand how this happens.

When mast cells are activated, they release a chemical called histamine. Histamine can be likened to an alarm system that alerts other immune cells to quickly head to the affected area. It also causes the blood vessels in that area to expand and increase their permeability, leading to swelling, redness and characteristic itching.

This condition is relatively rare, affecting 6 people out of every 10,000. But it may not be adequately diagnosed, because not all infected people experience severe symptoms.