Hives, also known as urticaria, refer to raised, red wheals or welts on your skin that are very itchy and can be accompanied by deep tissue swelling (angioedema).
Hives usually disappear within 24 hours but can reappear on another area of the skin, while the angioedema usually takes up to three days to resolve.
Although hives are not usually a sign of a serious underlying health condition, they can significantly affect your quality of life.
Hives are predominantly caused by immune cells in your skin called mast cells releasing a cocktail of chemicals, such as histamine and other mediators. Hives can be classified based on duration, and the role of definite triggers.
When defined by duration, hives can be acute, lasting up to six weeks, or chronic (long-term), lasting longer than six weeks.
Around one in five people will experience acute hives at some point in their life, most often as a child or adolescent; acute hives are also more likely if you have an atopic condition (eg asthma, eczema, hay fever).
Chronic hives affect around one in 50 people. They are more common in those of Asian or Latin American descent and slightly more common in women.
Classification by triggers
When defined by triggers, hives can be spontaneous or inducible.
Spontaneous hives occur without any identifiable trigger, while inducible hives can be caused by a wide variety of triggers, including scratching, minor trauma, cold, heat, UV light, pressure, vibration, contact, emotional stress, exercise, or water.
Hives can also be a symptom of another condition, such as a food allergy. In the case of an allergic reaction, hives typically occur alongside respiratory, cardiovascular and/or gastrointestinal symptoms (eg breathlessness, wheezing, dizziness, rapid heart rate (tachycardia), low blood pressure (hypotension), diarrhoea, vomiting, and/or stomach pain).
If you’re experiencing hives, you may not be able to tell if it's a symptom of an allergic reaction, or a condition on itself. If your hives are accompanied by respiratory or cardiovascular symptoms (eg breathlessness, wheezing, dizziness, and/or weakness), you should go to A&E immediately as you may be having an acute allergic reaction.
If you have hives without any other symptoms and after a few days, they’re not getting better, are spreading or keep coming back, or you generally feel unwell and have a fever, see your GP.
As other medical conditions can mimic hives, it’s important to have your symptoms assessed by a doctor.
If you’re concerned that you have hives, your GP will ask you questions to establish a detailed history of your symptoms and health.
If you don’t have hives when you see your doctor, it’s important to take photos when your hives occur, which you can later show to your GP.
Depending on your answers, your GP may need to request further investigations such as blood tests, in order to identify conditions that could be related to your hives and need treatment, or to rule out some rare causes.
The first line of treatment for hives is non-sedating antihistamines, which are usually taken once a day.
If this isn’t enough to relieve your symptoms, your GP may gradually increase the dose of the antihistamine to up to four times a day. You may be prescribed a short course of oral steroids to break the cycle of your symptoms.
In some cases, you may also need to take a leukotriene receptor antagonist, such as montelukast. If your hives are interfering with your ability to sleep, your doctor may prescribe a sedating antihistamine (ie one that makes you feel drowsy) to help you fall asleep.
If your hives still aren’t improving, your GP may refer you to a doctor who specialises in treating hives, such as allergist or dermatologist.
If the aforementioned treatments aren’t effective, the specialist doctor may add a monthly injection of a monoclonal antibody called omalizumab. If this injection cannot control your symptoms, you may be prescribed an immunosuppressive medication called ciclosporin.
Dr Iason Thomas is a Consultant Allergist at Spire Manchester Hospital and Manchester University NHS Foundation Trust and is also an Honorary Senior Lecturer at the University of Manchester. He has extensive experience in all aspects of allergy care, including anaphylaxis, asthma, drug allergy, eczema, food allergy, hay fever, hives, angioedema, latex allergy, and venom allergy. He also performs highly specialist work in the areas of general anaesthetic allergy, drug challenges, food challenges and immunotherapy (desensitisation).
If you're concerned about symptoms you're experiencing or require further information on the subject, talk to a GP or see an expert consultant at your local Spire hospital.