Medically Reviewed on 1/12/2021
What are hives?
Hives are itchy bumps that appear on your skin, usually as a result of an allergic reaction. Some cases of hives have no known cause.
Hives, also called urticaria, are bumps that appear on the skin quickly and often disappear as fast as they show up. They may be red or the color of your skin. These bumps can be itchy, and they occur in about 20% of people. They are triggered by a number of factors, many of which can be avoided.
Some people get urticaria as an allergic reaction while others get it without any known cause. Hives may take the appearance of a mosquito or bug bite. However, when they disappear, hives do not leave behind any marks. Although hives are uncomfortable, they are usually harmless and go away on their own.
They can appear anywhere on the body, including the face, lips, tongue, throat, or ears. People of all ages can get hives. If you think there is a need to seek medical attention about hives, take a picture of the affected area as they may disappear before your doctor examines you. The most effective treatment for urticaria is avoiding the trigger.
Signs and symptoms of urticaria
The symptoms of urticaria can last anywhere from minutes to months or years. They are not to be confused with bug bites. If you notice the following signs, then you might have hives:
- Red or skin-colored bumps that appear suddenly and may go away quickly might be hives.
- They appear on any area of the body and they may move around, change shape, disappear and come back over short periods of time.
- When you press the center of a red hive, it turns white (blanching).
Sometimes hives can appear as pink or red, surrounded by a red blotch. They can be an early sign of a whole-body reaction to an allergy. Look out for other symptoms like swelling of the tongue, lips, or face, which may signal a life-threatening condition known as anaphylaxis.
Urticaria is easily confused with angioedema, which involves swelling below the surface of your skin. Whereas urticaria is swelling on the skin’s surface.
Types of urticaria
There are two main subtypes of hives that have broader ramifications than an acute reaction, which is sometimes called acute or spontaneous hives:
If your hives last more than six weeks, they are considered chronic hives. Chronic hives are often associated with an immune response or a pre-existing condition, like thyroid disease, hormone imbalance, or cancer. In some cases the cause of the hives is unknown and is referred to as idiopathic urticaria.
Physical urticaria is caused by a physical stimulus, like temperature or pressure. This type of urticaria can manifest in several ways. A few common physical triggers of hives are scratching or rubbing, a drastic temperature change, extreme pressure, or sun exposure.
Causes of urticaria
Hives have a number of known triggers, many of which are considered allergens. They include:
- Some medications, such as antibiotics, aspirin, and ibuprofen
- Some food (especially peanuts, eggs, nuts, and shellfish)
- Physical stimuli, such as pressure, cold, heat, exercise, or sun exposure
- Insect stings from bees, wasps, yellow jackets, or fire ants
- Bacterial infections, including urinary tract infections and strep throat
- Viral infections, including the common cold
- Blood transfusions
- Irritants like latex, pet dander, or pollen
You may also get hives from vasculitis, or inflammation of the blood vessels. In this case, the hives will be more painful than itchy and may leave a bruise on the skin. These hives sometimes last more than a day.
When to see the doctor for urticaria
Hives are not a serious condition that needs emergency treatment. If they come and go, watch out for any trigger to avoid future incidents. If they persist, and you suspect a case of chronic urticaria, then you should see your doctor. Also, if you notice red bumps on your skin that look like hives but leave a mark after they disappear, tell your doctor about it.
If your episode is accompanied by other signs like dizziness, stomach cramps, swelling, or trouble breathing, call your doctor immediately as this could be a sign of serious allergic reaction.
If your case is just a single episode of hives, there will be no need for extensive testing. Usually keeping a record of your food intake is enough to identify the cause of acute hives.
An additional test may also be performed to confirm the diagnosis, especially if your urticaria is chronic. An allergist may do a skin-prick test to assess how your skin reacts to different stimuli. Once the trigger is identified, you’ll likely be advised to avoid that food or substance. However, even with testing, the cause of chronic hives is not always found.
Treatments for urticaria
For many people, over-the-counter antihistamines are an effective at-home treatment for spontaneous or acute hives. Also if you can track and identify your own trigger or allergen, avoiding that substance may be enough to prevent hives.
Persistent hives may call for you to see an allergist. They may recommend antihistamines to prevent the hives, rather than to use them only after an outbreak. But it may also be used to reduce the severity of your symptoms.
Your treatment depends on many factors including how uncomfortable the hives make you feel. Your doctor may also recommend cool compresses to relieve itching. If your case is severe, your doctor may use prednisone or a similar medication temporarily.
Preventing hives is personal and depends on avoiding what triggers you. But some general guidelines to prevent hives are:
- Avoid wearing tight clothing for long periods of time.
- Avoid any triggers you know you are allergic to.
- Use unscented soaps and body products.
- Limit prolonged sun exposure.
- Avoid extreme temperature changes.
Allergies can best be described as:
Medically Reviewed on 1/12/2021
The Allergy Center at Sacramento Ear, Nose & Throat: “Urticaria/Hives.”
American College of Allergy, Asthma & Immunology: “Hives (Urticaria).”
American Family Physician: “Hives: What You Should Know.”
American Family Physician: “Urticaria: Evaluation and Treatment.”
Genetic and Rare Diseases Information Center: “Hypocomplementemic urticarial vasculitis.”
Harvard Health Publishing: “Hives (Urticaria).”
Indian Journal of Dermatology: “Diagnosis of urticaria.”
National Jewish Health: “Hives (Urticaria).”
National Jewish Health: “Hives: Causes.”
University of Utah Health: “I’m Not Sure Why I Keep Getting Hives.”
U.S. National Library of Medicine: “Hives.”