Urticaria (hives): triggers, treatment and chronic spontaneous urticaria

The NHS describes the main symptom of hives as an itchy rash. The rash can be raised bumps or patches in many shapes and sizes, can appear anywhere on the body, may be on one area or spread across the body, can itch, sting or burn, and looks pink or red on white skin although the colour can be harder to see on brown and black skin. Individual patches often come and go within hours while new ones appear elsewhere.

The NHS explains the mechanism: hives happen when something causes high levels of histamine and other chemicals to be released in the skin. That cause is called a trigger. Allergy UK adds that in chronic spontaneous urticaria, immune cells called mast cells release histamine into the skin when they should not, producing itching, redness, swelling and the raised rash.

The NHS says you cannot always prevent hives, and lists triggers that include certain foods, contact with certain plants, animals, chemicals and latex, cold such as cold water or wind, hot or sweaty skin from exercise, emotional stress or spicy food, a reaction to a medicine, insect bite or sting, scratching or pressing on the skin such as from itchy or tight clothing, an infection, a problem with the immune system, and, rarely, water or sunlight.

It suggests trying to find out what triggers your hives so that you can avoid them if possible. This works for some short-lived episodes and for physical triggers such as cold or pressure, but Allergy UK warns that chronic spontaneous urticaria is different: it is not caused by allergens, and allergy testing, elimination diets and avoiding the usual triggers are not always useful in working out the cause or managing symptoms.

The NHS says a pharmacist can give advice about antihistamine treatment to help a hives rash, and that you should tell the pharmacist if you have a long-term condition because you might not be able to take antihistamines; treatment might also not be suitable for young children. Allergy UK suggests soothing the skin with cream-based emollients or anti-itch products, applying a cool compress or ice pack, taking a cool bath if cold does not make your symptoms worse, wearing loose lightweight clothing, and avoiding scratching because it releases more histamine and can make itching worse.

Allergy UK lists things that some people find worsen symptoms: stress, alcohol, caffeine, recreational drugs and extreme temperatures. It reminds readers to talk to a healthcare professional before stopping any prescribed medication.

The NHS says to ask for an urgent GP appointment or NHS 111 if hives do not improve after 2 days, you are worried about your child, the rash is spreading, hives keep coming back (you may be allergic to something), you have a high temperature and feel unwell, or you have swelling under your skin, which might be angioedema.

Call 999, according to the NHS, if your lips, mouth, throat or tongue suddenly swell, you are breathing very fast or struggling to breathe, your throat feels tight or swallowing is difficult, your skin, tongue or lips turn blue, grey or pale, you suddenly become very confused, drowsy or dizzy, someone faints and cannot be woken, or a child is limp, floppy or unresponsive. These can be signs of a serious allergic reaction that may need immediate treatment in hospital.

The NHS says a GP might prescribe menthol cream, antihistamines or steroid tablets, and that if hives does not go away with treatment you may be referred to a skin specialist (dermatologist). For chronic spontaneous urticaria, Allergy UK describes a stepped approach: a daily non-sedating antihistamine first, with the dose increased under the supervision of a healthcare professional if symptoms continue; then additional medication such as a leukotriene receptor antagonist, and occasionally a short course of corticosteroid tablets for severe flare-ups (repeated courses can have adverse long-term effects, so they are not given frequently); and for people whose symptoms stay difficult to control, biologic therapies or immunosuppressants such as ciclosporin started by specialist hospital teams, with blood-test monitoring for the latter.

Never raise an antihistamine dose on your own. The dose escalation described by Allergy UK is only for use under a clinician's direction, and the right medicine depends on your other conditions and what else you take.

Allergy UK describes CSU as a chronic skin condition causing recurrent hives and sometimes swelling, without an obvious trigger. Symptoms must be present for at least six weeks before it can be diagnosed, and, because it can come and go, it may take more than one appointment to confirm. Some people have symptoms for a relatively short period, others for several years, and it cannot be predicted. There is currently no cure, but treatment focuses on controlling symptoms and improving quality of life.

It can affect sleep, mood, social life, work, relationships and confidence. Allergy UK suggests preparing for appointments by noting when symptoms started, how often and how long they last, what makes them better or worse, taking photographs of rash or swelling, and listing all medicines and supplements. A GP may ask about your history, arrange tests to rule out other conditions, ask you to keep a symptom diary and use a symptom scoring tool. Its booklet received sponsorship funding from a pharmaceutical company, which it states had no input into the content.

Short-lived hives are managed through pharmacies and GPs on the NHS. Persistent or severe urticaria can be referred to dermatology or allergy clinics, where biologic treatments are provided under NHS funding rules.

Private dermatology or allergy consultations can speed up assessment. Since chronic spontaneous urticaria is not an allergy and broad allergy panels often add little, ask what each test is expected to show and avoid expensive elimination diets without a clear reason.