Almost any medicine can cause urticaria, but painkillers (especially aspirin, ibuprofen, diclofenac), antibiotics (especially penicillin group antibiotics), blood products and vaccinations are commonly reported as causes.
Angioedema, in particular, can be caused by a type of drug (ACE inhibitors) used to lower blood pressure and protect the heart.
In some patients with chronic spontaneous urticaria, the release of histamine from skin mast cells is triggered by factors circulating in the blood, such as antibodies directed against their own mast cells, a process known as autoimmunity. A skin test or blood test maybe performed to detect the presence of this condition.
Urticaria is not hereditary although a rare form of angioedema (hereditary angioedema) can run in families. In a small percentage of people, foods, colouring agents and preservatives appear to worsen urticaria, and it might be helpful to identify these by keeping a food diary. These substances can be omitted from the diet to see if the condition improves, and later reintroduced to confirm whether they are the cause of the urticaria. However, as urticaria fluctuates frequently, this is not always accurate.
Urticaria is often thought to be related to allergy, but in fact, allergy is not the commonest cause of urticaria. Second generation non-sedating oral antihistamines are safe and often effective in managing urticaria when taken regularly. The older generation antihistamines tend to cause drowsiness and does not allow for safe operation of machineries or vehicles. In fact the older generation antihistamines and even some of the second generation antihistamines are not deemed safe for pilots to consume prior to flying, as ruled by the United States Federal Aviation Administration. In the presence of autoimmunity, stronger immunosuppressive medications maybe used under close specialist supervision to provide relief.