What is chronic urticaria?
Chronic urticaria refers to when the urticaria and/or angioedema episodes persist for longer than 6 weeks. At any given time it is believed to affect 0.5-1% of the global population.
When a cause cannot be found, it is called ‘spontaneous’ but may have an autoimmune element to it (see below).
Another subtype of chronic urticaria are ‘inducible urticarias’ – since the weals may be set off (or “induced”) by a physical trigger, such as cold, pressure or friction. The weals usually occur within minutes, and last for less than one hour (except delayed pressure urticaria, which is delayed in onset and lasts for hours at least). They often occur in otherwise healthy young adults but can affect any age.
They include the following types:
- Symptomatic dermographism (“skin writing”) – itchy weals occur after friction, such as rubbing or stroking the skin
- Cold urticaria – itchy weals are triggered by exposure to cold, including rain, wind and cold water – swimming in cold water may be dangerous
- Cholinergic urticaria – itchy weals are triggered by sweating, following exertion, hot showers, emotional stress or eating spicy food.
- Contact urticaria – various chemicals, foods, plants, animals, and animal products, can cause weals within minutes at the site of contact.
- Delayed pressure urticaria – itchy weals develop where pressure has been applied to the skin, for example from tight clothes or from gripping tools. Usually the swelling develops several hours later. It can be painful and lasts longer than a day.
- Solar urticaria – itching and weals occur on the skin immediately after exposure to sunlight. It is rare.
- Aquagenic urticaria -small weals occur on the skin at the site of contact with water. It is extremely rare.
What causes it?
Chronic spontaneous urticaria (CSU) by definition does not have a cause but may have an autoimmune element to it, where a patient’s own antibodies are responsible for releasing histamine from mast cells. There may be a personal history or family history of other auto-immune conditions accompanying it.
What are the treatment options available?
The treatment of chronic urticarias includes the use of regular high dose antihistamines and additional medications such as montelukast. However, a significant number of patients will remain symptomatic and require additional treatments.
These might include:
- Omalizumab monthly injections. Omalizumab (a recombinant, humanized anti-IgE antibody) is an add on therapy for the treatment of CSU in adults and adolescents with an inadequate response to treatment with antihistamines.
- Immunosuppressants e.g. ciclosporin medication