Urticaria (Hives)
Urticaria – also known as hives, weals, welts or nettle rash – is a raised, itchy rash that appears on the skin. It may appear on one part of the body or be spread across large areas.
The rash is usually very itchy and ranges in size from a few millimetres to the size of a hand.
Although the affected area may change in appearance within 24 hours, the rash usually settles within a few days.
Types of urticaria
Doctors may refer to urticaria as either:
- acute urticaria – if the rash clears completely within 6 weeks
- chronic urticaria – in rarer cases, where the rash persists or comes and goes for more than 6 weeks, often over many years
Psoriasis can affect the joints too. Smaller A much rarer type of urticaria, known as urticaria vasculitis, can cause blood vessels inside the skin to become inflamed. In these cases, the weals last longer than 24 hours, are more painful, and can leave a bruise.of the hand and joints of the knee and lower back can also get involved. If joint pain develops then it is important to see a dermatologists as early treatment can prevent joint deterioration.
Who’s affected by urticaria?
Acute urticaria (also known as short-term urticaria) is a common condition, estimated to affect around 1in 5 people at some point in their lives.
Children are often affected by the condition, as well as women aged 30 to 60, and people with a history of allergies.
What causes urticaria?
Urticaria occurs when a trigger causes high levels of histamine and other chemical messengers to be released in the skin. These substances cause the blood vessels in the affected area of skin to open up (often resulting in redness or pinkness) and become leaky. This extra fluid in the tissues causes swelling and itchiness.
Histamine is released for many reasons, including:
- an allergic reaction – like a food allergy or a reaction to an insect bite or sting
- cold or heat exposure
- infection – such as a cold
- certain medications – like non-steroidal anti-inflammatory drugs (NSAIDs) or antibiotics