What is cold urticaria?
Cold urticaria is a relatively uncommon physical urticaria. An urticarial rash develops after being exposed to cold, cold water, and cold objects.
Acquired cold urticaria is now understood to be a completely different disorder from familial cold autoinflammatory syndrome (FCAS), previously known as hereditary cold urticaria. FCAS is one of the cryopyrin-associated periodic syndromes.
What causes cold urticaria?
Cold urticaria is caused by exposure to cold. Why the cold stimulus causes the activation of mast cells and subsequent release of histamine and other inflammatory mediators remains unknown.
Cold urticaria may be primary (idiopathic) or secondary to an underlying haematologic (blood condition) or infectious disease. Most cases are of the idiopathic (unknown cause) type.
Underlying conditions that have been associated with secondary cold urticaria include:
- chronic lymphocytic leukaemia
- chickenpox (varicella)
- viral hepatitis
- infectious mononucleosis (glandular fever).
What are the clinical features of cold urticaria?
Symptoms of cold urticaria become obvious within 2-5 minutes after exposure and last for 1-2 hours. They include:
- Itchy weals (urticaria) and angioedema that may be localised (affecting certain parts of the body) or generalised (rash over the whole body).
- In some cases systemic symptoms may develop
- Shortness of breath, wheezing
- Abdominal pain, gastrointestinal ulcers
- Rapid and irregular heartbeat
- In very severe cases hypotension (drop in blood pressure), shock, collapse and even death may occur.
Swimming in cold water is the most common cause of a severe cold urticarial reaction.
Who gets cold urticaria?
Acquired cold urticaria most often affects young and middle-aged adults, but it may present in children or the elderly. It is commonly associated with the physical urticarias dermographism and cholinergic urticaria, and sometimes with ordinary urticaria. Cold urticaria usually lasts for some years. About 30% report resolution of symptoms within 5 to 10 years.
How is the diagnosis made?
Cold urticaria can be diagnosed by applying an ice cube against the skin of the forearm for 1-5 minutes. A distinct red swollen rash should develop within minutes in the area exposed to the cold-stimulation test if a patient has cold urticaria. Complete blood counts and metabolic tests may also be performed to determine associated diseases.
Cold urticaria – ice-cube test
What is the treatment for cold urticaria?
Patients with cold urticaria should learn to protect themselves from a rapid drop in body temperature. Aquatic activities (e.g. swimming, surfing) should be done under supervision at all times.
Regular doses of conventional antihistamines have generally proven to be ineffective, but high doses of non-sedating antihistamines may be helpful (e.g., four times the usual dose). Some related medications that have been found to be useful include cyproheptadine, doxepin and ketotifen.
Cautious induction of cold tolerance may be successful (desensitisation), by gradually hardening the skin to cold conditions and then exposing the skin to it regularly e.g., by taking regular cold showers.