Medically reviewed by Chris Schwerdt. Last updated on May 29, 2025
General Illness Information
Common Name:
Hives
Medical Term: Urticaria
Description: Disorder characterized by a skin rash with raised areas with redness and itching. Commonly allergic but may also occur on a non-allergic basis.
Causes:
- Allergic or non-allergic; massive histamine release from mast cells in skin;
- Drug reaction especially Aspirin, Non-steroidal anti- inflammatory drugs;
- Food or food additive allergy;
- Allergy to peanuts and/or tree nuts a leading cause of severe (sometimes fatal) food-induced allergic reactions. Affects 1% of the general population. Other foods that cause hives are chocolate, fish, tomatoes, eggs, fresh berries, milk. Also food additives and preservatives;
- Inhalant, contact allergy;
- Transfusion reaction;
- Insect bite, sting;
- Infection – viral upper respiratory infections (esp. in children) and infectious mononucleosis, viral hepatitis; bacterial (strep throat, sinusitis, dental abscess, otitis); vaginitis; fungal ; helminthic; protozoan. Helicobacter pylori has been increasingly associated with, and its eradication may stop, chronic urticaria;
- Collagen vascular disease (cutaneous vasculitis, serum sickness, lupus);
- Thyroid autoimmunity often associated. Administering thyroid hormone may alleviate chronic urticaria in hypothyroid patients with autoantibodies;
- Physical trauma (heat, cold, sunlight, etc.);
- Emotional stress.
Prevention:
- If you have had hives and identified the cause, avoid the source;
- Keep an anaphylaxis kit if you experience severe reactions.
Signs & Symptoms
Itchy skin papules (small, raised bumps) with the following characteristics:
- They swell and produce pink or red lesions called wheals. Wheals have clearly defined edges and flat tops. They measure 1 cm to 5 cm in diameter;
- Wheals join together quickly and form large, flat plaques (larger areas of raised, skin-colored lesions);
- Wheals and plaques change shape, resolve and reappear in minutes or hours. This rapid change is unique to hives.
Risk Factors
Diagnosis & Treatment
This is a clinical diagnosis. Laboratory studies not usually helpful.
General Measures:
- Emergency room care for life threatening reactions like difficulty swallowing, talking or breathing;
- Laboratory studies are not usually helpful in the evaluation of acute or chronic reactions unless there are suggestive findings in the history and physical examination;
- Cause of chronic reaction is rarely found;
- Treatment aims are to prevent contact with the triggering factors;
- Allergy skin tests are usually not helpful;
- Desensitization injections are useful only when a specific allergen is found on skin testing;
- Don’t take drugs (including aspirin, laxatives, sedatives, vitamins, antacids, pain killers or cough syrup) not prescribed for you;
- Don’t wear tight underwear or foundation garments. Any skin irritation may trigger new outbreaks;
- Hot baths or showers may aggravate the condition;
- Apply cold-water compresses or soaks to relieve itching;
- Using colloidal oatmeal in a tepid bath may help relieve the itching.
Medications:
- Mainstay of treatment is antihistamines. Sometimes combination of antihistamines will be more helpful;
- For rapidly progressing acute urticaria subcutaneous injection of epinephrine is used;
- Corticosteroids may sometimes need to be prescribed for a severe acute reaction;
- Tricyclic antidepressants appear to be effective in some cases of chronic urticaria.
Activity:
As desired. Avoid overheating.
Diet:
As desired. Avoid foods implicated as possible etiologic agents.
Possible Complications:
Severe systemic allergic reaction (bronchospasm, anaphylaxis).
Prognosis
- Of all patients with acute urticaria, 70% will be better in < 72 hours. 30% will become chronic;
- 20% have attacks for > 20 years.
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