Hives (urticaria)

Hives (urticaria) are raised, itchy welts on the skin that appear suddenly and usually fade within hours, though new welts may continue to appear. Acute hives last less than six weeks; chronic urticaria lasts six weeks or longer. Hives often result from an allergic or pseudoallergic reaction, infection, or physical triggers, but in many chronic cases no specific cause is found (chronic spontaneous urticaria).

Angioedema — deeper swelling of eyelids, lips, tongue, or extremities — can accompany hives and, when it involves the throat, can be dangerous. Most acute hives are self-limited. Chronic hives are managed with antihistamines and, when needed, advanced therapies. Identifying and avoiding triggers helps when a cause is known.

Features of hives include:

• Raised, red or skin-colored welts (wheals) of varying size and shape
• Intense itching; sometimes burning or stinging
• Welts that blanch (turn white) when pressed
• Individual lesions that typically resolve within 24 hours, with new ones appearing elsewhere
• Possible angioedema — swelling of lips, eyelids, hands, feet, or genitals
• In severe allergic reactions: difficulty breathing, throat tightness, dizziness (anaphylaxis — emergency)

Chronic urticaria may fluctuate daily for months or years and significantly affect sleep and quality of life.

Acute hives are often triggered by:

• Foods (nuts, shellfish, eggs, milk, and others)
• Medicines (antibiotics, NSAIDs, aspirin, ACE inhibitors for angioedema)
• Insect stings or bites
• Infections (viral infections are common triggers, especially in children)
• Latex or other contact allergens

Physical urticarias are triggered by pressure, cold, heat, sunlight, vibration, or exercise (including cholinergic urticaria). Chronic spontaneous urticaria is often autoimmune or idiopathic. Stress can aggravate symptoms but is rarely the sole cause.

Risk factors include a history of allergies or atopic disease, family history of hives or angioedema, certain autoimmune conditions (thyroid disease, celiac disease, SLE), and viral infections. Women are more often affected by chronic spontaneous urticaria than men.

Complications include:

• Anaphylaxis when hives are part of a systemic allergic reaction
• Sleep disruption and impaired daily functioning from chronic itch
• Side effects from long-term medication use
• Anxiety related to unpredictability of outbreaks
• Rarely, underlying systemic disease associated with chronic urticaria

When triggers are identified:

• Avoid known food, drug, or physical triggers
• Read labels and inform clinicians of drug allergies
• Carry and know how to use epinephrine auto-injector if prescribed for anaphylaxis risk
• For chronic urticaria, consistent use of prescribed preventive antihistamines often reduces outbreaks even when no trigger is found

Diagnosis is primarily clinical. History focuses on timing, triggers, foods, medicines, infections, and associated angioedema or systemic symptoms. Limited blood tests may be used in chronic urticaria (CBC, CRP/ESR, thyroid tests, and others as indicated). Allergy testing is useful when history suggests a specific allergic trigger but is often unrevealing in chronic spontaneous urticaria. Skin biopsy is reserved for atypical features suggesting urticarial vasculitis or other diagnoses.

Seek emergency care for hives with difficulty breathing, throat swelling, dizziness, or collapse (possible anaphylaxis). See a clinician for hives that are widespread, painful, accompanied by fever, or lasting more than a few days, or for any chronic recurrent hives. A specialist (allergist or dermatologist) can help with chronic or complex cases.

Acute hives

• Second-generation H1 antihistamines (cetirizine, loratadine, fexofenadine, bilastine, etc.)
• Short course of oral corticosteroids for severe widespread episodes (not for repeated long-term use)
• Epinephrine and emergency care for anaphylaxis
• Discontinue implicated drugs or foods

Chronic spontaneous urticaria

• Second-generation H1 antihistamines, with dose increase up to 4× standard when needed and tolerated (per guidelines)
• Add-on omalizumab (anti-IgE) for antihistamine-refractory disease
• Cyclosporine or other immunosuppressants in selected refractory cases under specialist care
• Avoid NSAIDs if they worsen symptoms; manage stress and comorbidities

Physical urticarias are managed by trigger avoidance and antihistamines; specialized approaches apply for some subtypes.

Helpful measures:

• Take antihistamines regularly as prescribed for chronic disease, not only when welts appear
• Use cool compresses or cool showers for itch relief
• Wear loose, soft clothing
• Avoid known triggers, hot baths, and alcohol if they worsen symptoms
• Keep a symptom diary to identify patterns
• Moisturize if skin is dry
• Seek urgent care for any breathing or swallowing difficulty

Bring:

• Photos of the rash when present
• Timeline of outbreaks and possible triggers (foods, medicines, infections, physical factors)
• List of all medicines and supplements
• Personal and family history of allergies or autoimmune disease
• Questions about antihistamine dosing, omalizumab, and when to use emergency medication