Hives (Urticaria)

Causes

• Allergens: Foods (e.g., peanuts, shellfish, eggs, milk), medications (e.g., penicillin, aspirin), insect stings, latex.
• Physical stimuli: Pressure, cold, heat, sunlight, vibration, exercise. This is known as physical urticaria.
• Medications: Prescription and over-the-counter drugs.
• Infections: Viral, bacterial, or fungal infections.
• Insect bites and stings.
• Contact with certain substances: Plants (e.g., poison ivy), chemicals.
• Stress.
• Autoimmune conditions.
• In some cases, the cause of hives cannot be identified (idiopathic urticaria).

Symptoms

• Be itchy (pruritic), sometimes intensely so.
• Vary in size, from small spots to large patches.
• Appear anywhere on the body, including the face, lips, tongue, throat, and ears.
• Change shape, move around, and disappear within hours, only to reappear elsewhere.
• Sometimes join together to form larger raised areas.
• Be accompanied by angioedema, which is swelling in the deeper layers of the skin, often around the eyes, lips, or genitals.

Diagnosis

• When the hives started and how long they last.
• Possible triggers, such as foods, medications, or environmental exposures.
• Other symptoms you may have.

• Allergy testing: Skin prick tests or blood tests to identify specific allergens.
• Blood tests: To check for underlying medical conditions.
• Skin biopsy: Rarely needed, but may be done to rule out other skin conditions.
• Provocation testing: For physical urticaria, this involves exposing the skin to suspected physical triggers (e.g., applying pressure, ice).

Treatment

• Avoidance of triggers: Identifying and avoiding known triggers is crucial.
• Medications:
  • Antihistamines: These are the first-line treatment for hives and work by blocking histamine release. Non-sedating antihistamines are usually preferred for daytime use.
  • H2 blockers (histamine H2 receptor antagonists): May be used in combination with H1 antihistamines, particularly for chronic hives.
  • Corticosteroids (oral or topical): May be prescribed for severe acute hives to reduce inflammation, but are not typically used long-term due to potential side effects.
  • Leukotriene receptor antagonists: Can be helpful in some cases, especially when asthma or allergic rhinitis is also present.
  • Omalizumab: An injectable medication that targets IgE antibodies and is used for chronic spontaneous urticaria that doesn't respond to antihistamines.
  • Cyclosporine and other immunosuppressants: May be used for severe chronic urticaria that is resistant to other treatments.
• Cool compresses or showers: Can help soothe itchy skin.
• Loose-fitting clothing: Avoid tight or irritating clothing.

Prevention

• Keeping a food and symptom diary to track potential food allergies.
• Informing healthcare providers about any medication allergies.
• Avoiding known physical triggers if you have physical urticaria.
• Managing stress.

Getting Hives Under Control

Most acute hives resolve on their own and never need a cause found. Hives that keep returning for more than six weeks are a different problem, and the usual mistakes are chasing an allergy that is not there and underdosing the one treatment that works.

Antihistamines, at a dose that actually works

A non-sedating antihistamine such as cetirizine, fexofenadine, or loratadine taken every day, not only when welts appear, is the foundation. When the standard dose is not enough, guidelines support increasing it stepwise up to four times the package dose under supervision before anything else is added. Sedating antihistamines such as diphenhydramine add drowsiness, falls, and confusion in older adults without adding control. Prednisone settles a severe flare within a day but is limited to a few days, because repeated courses bring rebound and steroid side effects.

Chronic hives are rarely an allergy

Hives that come and go daily for weeks are almost never caused by a food, and broad allergy panels mostly produce false positives and needless diets. Chronic spontaneous urticaria is usually the immune system activating its own mast cells, sometimes alongside Hashimoto's thyroiditis, which is why a thyroid test and a simple blood count are the only routine workup. Our chronic hives article walks through what is and is not worth testing.

What quietly makes them worse

NSAIDs such as ibuprofen and naproxen, alcohol, heat, tight clothing, friction, stress, and poor sleep each lower the threshold for welts. Florida adds its own triggers: exercise and heat bring on the small, prickling welts of cholinergic urticaria, and a bite from the lone star tick can cause hives hours after eating red meat, the alpha-gal syndrome that is often missed because the delay is so long. Our sting allergy guide separates the large local swelling of fire ant and wasp stings from true allergy.

When antihistamines are not enough

Omalizumab, a monthly injection, controls most chronic hives that have failed high-dose antihistamines, and dupilumab is a newer option. Both are given through our immunology team or an allergist. Chronic hives typically burn out over a few years, so treatment is stepped down periodically to see whether it is still needed.

When it is not hives, and when it is an emergency

A welt that stays in one place longer than a day, leaves a bruise, or is painful rather than itchy may be urticarial vasculitis and needs a biopsy. Swelling of the lips, tongue, or face without any itchy welts, especially in someone taking an ACE inhibitor such as lisinopril, is a drug reaction rather than urticaria and the medication is stopped. Hives with throat tightness, wheeze, vomiting, or faintness is anaphylaxis: use epinephrine if prescribed and call 911. Welts that look like eczema or contact dermatitis but last for days are those conditions, not hives. NIAID and the American College of Allergy, Asthma and Immunology publish patient guidance on treatment.

If hives have returned most days for more than six weeks, or a daily antihistamine is not holding them, schedule a visit.