Hives, also known as urticaria, affects about 20 percent of people at some time during their lives. It can be triggered by many substances or situations and usually starts as an itchy patch of skin that turns into swollen red welts. The itching may be mild to severe. Scratching, alcoholic beverages, exercise and emotional stress may worsen the itching.
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Symptoms can last anywhere from minutes to months – or even years.
While they resemble bug bites, hives (also known as urticaria) are different in several ways:
Chronic hives occur almost daily for more than six weeks and are typically itchy. Each hive lasts less than 24 hours. They do not bruise nor leave any scar.
If your hives last more than a month or if they recur over time, see an allergist, who will take a history and perform a thorough physical exam to determine the cause of your symptoms. A skin test and challenge test may also be needed to identify triggers.
Therapies range from cool compresses to relieve itching to prescription antihistamines and other drugs, such as anti-inflammatory medications and medications that may modify your immune system.
Angioedema – swelling of tissue beneath the surface of the skin – can be mistaken for or associated with hives. It can be caused by allergic reactions, medications or a hereditary deficiency of some enzymes. The following symptoms may indicate angioedema:
An allergist can diagnose and treat both hives and angioedema.
In some cases, the trigger is obvious – a person eats peanuts or shrimp, and then breaks out within a short time. Other cases require detective work by both the patient and the physician because there are many possible causes. In a few cases, the cause cannot be identified.
A single episode of hives does not usually call for extensive testing. If a food allergy is suspected, consider keeping track of what you eat. This will help you discover whether there is a link between what you’re eating and when you break out with hives.
Chronic hives should be evaluated by an allergist, who will ask about your and your family’s medical history, substances to which you are exposed at home and at work, exposure to pets or other animals and any medications you’ve taken recently. If you have been keeping a food diary, show it to your allergist.
Your allergist may want to conduct skin tests, blood tests and urine tests to identify the cause of your hives. If a specific food is the suspected trigger, your allergist may do a skin-prick test or a blood test to confirm the diagnosis; once the trigger is identified, you’ll likely be advised to avoid that food and products made from it. In rare instances, the allergist may recommend an oral food challenge – a carefully monitored test in which you’ll eat a measured amount of the suspected trigger to see if hives develop. If a medication is suspected as the trigger, your allergist can conduct similar tests, and a cautious drug challenge – similar to an oral food challenge, but with medications – may also be needed to confirm the diagnosis. Because of the possibility of anaphylaxis, a life-threatening allergic reaction, these challenge tests should be done only under strict medical supervision, with emergency medication and equipment at hand.
In cases where vasculitis may be the cause, your allergist may conduct a skin biopsy and send it to a dermatopathologist to examine under a microscope.
The cause of chronic hives is often difficult to identify.
In many cases, treatment isn’t needed for urticaria, because the rash often gets better within a few days.
If the itchiness is causing you discomfort, antihistamines can help. Antihistamines are available over the counter at pharmacies – speak to your pharmacist for advice.
A short course of steroid tablets (oral corticosteroids) may occasionally be needed for more severe cases of urticaria.
If you have persistent urticaria, you may be referred to a skin specialist (dermatologist). Treatment usually involves medication to relieve the symptoms, while identifying and avoiding potential triggers.
Read about treating urticaria.
Around a quarter of people with acute urticaria and half of people with chronic urticaria also develop angioedema, which is a deeper swelling of tissues.
Chronic urticaria can also be upsetting and negatively impact a person’s mood and quality of life.
Angioedema is swelling in the deeper layers of a person’s skin. It’s often severe and is caused by a build-up of fluid. The symptoms of angioedemacan affect any part of the body, but usually affect the:
Medication such as antihistamines and short courses of oral corticosteroids (tablets) can be used to relieve the swelling.
Read more about treating angioedema.
Living with any long-term condition can be difficult. Chronic urticaria can have a considerable negative impact on a person’s mood and quality of life. Living with itchy skin can be particularly upsetting.
One study found that chronic urticaria can have the same negative impact as heart disease. It also found that one in seven people with chronic urticaria had some sort of psychological or emotional problem, such as:
See your GP if your urticaria is getting you down. Effective treatments are available to improve your symptoms.
Talking to friends and family can also improve feelings of isolation and help you cope better with your condition.
Read about how talking to others can help.
Urticaria can be one of the first symptoms of a severe allergic reaction known as anaphylaxis.
Other symptoms of anaphylaxis include:
Anaphylaxis should always be treated as a medical emergency.
Call 999 immediately and ask for an ambulance if you or someone else is experiencing anaphylaxis. Tell the operator about your (or their) symptoms.
Researchers have identified many – but not all – of the factors that can cause hives. These include food and other substances you take, such as medications. Some people develop hives just by touching certain items. Some illnesses also cause hives. Here are a few of the most common causes:
Antihistamines – available either over the counter or by prescription – are a frequently recommended treatment for hives. They work by blocking the effect of histamine, a chemical in the skin that can cause allergy symptoms, including welts. Low-sedating or nonsedating antihistamines are preferred. They are effective and long-lasting (may be taken once a day) and have few side effects. Your allergist may recommend a combination of two or three antihistamines to treat your hives, along with cold compresses or anti-itch salves to ease the symptoms.
Severe episodes of urticaria may require temporary treatment with prednisone, a similar corticosteroid medication or an immune modulator, which can reduce the severity of the symptoms.
If your reaction involves swelling of your tongue or lips, or you have trouble breathing, your allergist may prescribe an epinephrine (adrenaline) auto-injector for you to keep on hand at all times. These can be early symptoms of anaphylaxis, a potentially fatal allergic reaction that impairs breathing and can send the body into shock. The only treatment for anaphylaxis is epinephrine. If you develop hives and your injector is not nearby – or if using the auto-injector doesn’t cause the symptoms to immediately improve – go to an emergency room immediately. You should also go to the emergency room after using an auto-injector.
If the cause of hives can be identified, the best treatment is to avoid the trigger or eliminate it:
The best treatment for hives and angiodema is to identify and remove the trigger, but this is not an easy task. Antihistamines are usually prescribed by your doctor to provide relief from symptoms. Antihistamineswork best if taken on a regular schedule to prevent hives from forming in the first place.
Chronic hives may be treated with antihistamines or a combination of medications. When antihistamines don’t provide relief, oral corticosteroids may be prescribed. A biologic drug, omalizumab (Xolair), is also approved to treat chronic hives in those at least 12 years of age.
While you’re waiting for hives and swelling to disappear, here are some tips:
If hives or angioedema occur with any of the following symptoms, contact your doctor right away:
Visit your GP if your symptoms don’t go away within 48 hours.
You should also contact your GP if your symptoms are:
Acute urticaria (also known as short-term urticaria) is a common condition, estimated to affect around one in five people at some point in their lives.