Demystifying Hives and Chronic Urticaria

Hives are a common skin condition, presenting as a rash of red, swollen patches accompanied by itching, burning or stinging sensations. The swollen patches sometimes coalesce to form large, swollen areas.

Hives have clearly defined contours and are usually smooth on the surface and slightly raised. When the reddened skin is pressed, the centre turns white. Plaques may remain for minutes or hours, then disappear, only to reappear elsewhere. Once the hives have disappeared, the skin returns to its normal appearance. Each patch usually resolves within 24 hours.

In addition to plaques, hives can be accompanied by swelling under the skin, sometimes affecting the face, lips or throat. This is known as angioedema.

Hives and angioedema may be allergic reactions. You should consult your doctor if symptoms are severe, last more than two days or are accompanied by other symptoms such as fever, joint pain or night sweats.

If you or a family member have hives that go away on their own and don’t come back, there’s usually no need to see a doctor.

Acute urticaria  usually lasts six weeks or less. When symptoms last longer than 6  weeks (1 % of cases), we speak of chronic urticaria. Chronic urticaria, however, can last for months or years, then disappear for no apparent reason.

If a cause can be identified, acute urticaria is most often caused by :

Chronic urticaria is an inflammatory skin disease, probably of autoimmune (100 % non-allergic) etiology (cause); that is, the organism’s immune system goes haywire and releases histamine by various mechanisms. However, urticaria has been associated with other autoimmune diseases such as thyroid disease, rheumatoid arthritis, lupus, Sjögren’s syndrome, celiac disease and type  1 diabetes.

Chronic urticaria can be induced by a variety of factors, such as pressure, cold or heat. This is known as inducible chronic urticaria. In theory, the possible identifiable causes of other forms of chronic urticaria are the same as those of acute urticaria. However, in the vast majority of cases, the cause cannot be identified. This is known as spontaneous or idiopathic chronic urticaria. Most cases of spontaneous chronic urticaria are thought to be due to an autoimmune reaction, which itself has no detectable cause.

Sometimes, the cause is easily overlooked, as when people repeatedly consume a food that is not considered a trigger, such as a preservative or colouring agent in food, or penicillin in milk. Often, despite our best efforts, the etiology remains unknown.

Epidemiologically, chronic urticaria is more common in adults and women. It is estimated that 20-30 % of acute urticaria cases in infants and young children will become chronic urticaria.

We know that emotional stress can precipitate and exacerbate chronic urticaria, and that urticaria itself can be a source of great stress when it affects patients’ quality of life. Some patients only develop urticaria when they are experiencing stressful situations. Avoiding stress factors can help control symptoms.