Hives (Urticaria)
Also known as: Urticaria, Wheals, Welts
What are hives?
Hives, or urticaria, is a very common skin reaction marked by the sudden appearance of red or pink patches, slightly raised, that resemble nettle stings. These lesions, called wheals, usually cause intense itching and can appear anywhere on the body. In most cases the reaction is short-lived, and an individual hive fades within 24 hours, though new ones can keep appearing. When hives continue for six weeks or longer, the condition is called chronic hives.
Causes and risk factors
Hives result from the release of histamine by immune cells called mast cells. Histamine and related mediators widen blood vessels and make them leakier, which causes the skin to swell locally into wheals. Triggers are numerous: food allergies (shellfish, nuts, eggs, peanuts), medications (antibiotics such as penicillin and sulfa drugs, anti-inflammatories such as aspirin and ibuprofen), viral or bacterial infections, insect stings, exposure to cold or heat, intense physical exertion, and emotional stress. In most chronic cases, no specific cause is ever identified.
Symptoms
Hives have characteristic, easily recognizable signs:
- Raised red or skin-colored patches with well-defined edges
- Intense itching
- Patches that blanch, turning white in the center when pressed
- Lesions that move, with each individual hive fading within 24 hours as new ones appear elsewhere
- Possible swelling of the lips, eyelids, or throat (angioedema)
The patches can be few in number or cover large areas of the body. Their fleeting, migratory appearance is a key feature that helps with diagnosis.
Diagnosis
A doctor generally diagnoses hives from a clinical exam and your history. They will try to identify the trigger by reviewing the pattern of episodes, medications taken, diet, and recent activities. For chronic hives, bloodwork may be ordered to look for an underlying cause such as an infection or an autoimmune disorder, though extensive routine testing is usually unnecessary because most chronic cases have no identifiable external cause. Skin allergy testing may also be considered.
Available treatments
Managing hives relies first on avoiding the trigger when one is identified. On the medication side, second-generation antihistamines (cetirizine, loratadine, fexofenadine) are the first-line treatment, taken on a regular schedule. Non-drowsy antihistamines are preferred, and an allergist may combine more than one if a single drug is not enough. For severe swelling, a doctor may prescribe a short course of oral corticosteroids. For chronic hives that persist despite antihistamines, the FDA has approved omalizumab for chronic spontaneous urticaria in people 12 and older, though it can take four to six months of treatment before the skin clears. Anti-itch creams containing menthol, calamine, or pramoxine can relieve itching locally.
Prevention and practical tips
When a trigger is identified, avoiding it remains the most effective preventive measure: find the trigger and avoid it, and you can prevent new hives from forming. If hives last more than a few days or keep coming back, keep a journal of episodes to spot recurring elements such as foods, environments, or activities. During a flare, wear loose-fitting, 100% cotton clothing, take warm rather than hot baths and showers since hot water irritates the skin, and use only gentle, fragrance-free soaps and skin care products. Try not to scratch, which can trigger more hives. People prone to severe flares may be advised to carry a fast-acting antihistamine, or an epinephrine auto-injector if a risk of anaphylaxis has been identified.
When should you see a doctor?
Certain signs call for prompt medical care, or for calling 911 as an emergency: swelling of the face, lips, or tongue, difficulty swallowing or breathing, shortness of breath, feeling faint, or loss of consciousness. Hives can cause dangerous swelling in the airway, which is a medical emergency. These symptoms can indicate a severe anaphylactic reaction requiring immediate care.
Sources
- American Academy of Dermatology (AAD), hives overview, symptoms, chronic-hives threshold, and emergency warning signs
- American Academy of Dermatology (AAD), treatment: antihistamines, oral corticosteroids, omalizumab (12 and older, 4 to 6 months to clear), and anti-itch creams with menthol, calamine, or pramoxine
- American Academy of Dermatology (AAD), self-care: loose cotton clothing, warm (not hot) baths, gentle fragrance-free products, and not scratching
- American College of Allergy, Asthma & Immunology (ACAAI), triggers (foods, medications, infections, physical stimuli), blanching, angioedema, and epinephrine for anaphylaxis risk
- MedlinePlus, U.S. National Library of Medicine: general overview and dangerous airway swelling as a medical emergency
- StatPearls, NCBI Bookshelf (NIH), chronic urticaria clinical review: mast-cell and histamine mechanism, second-generation antihistamines as first-line, and omalizumab for chronic spontaneous urticaria