Urticaria (Hives) — Causes, Symptoms & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Urticaria, commonly called hives, is a common skin reaction characterized by raised, itchy wheals (welts) that appear suddenly, are pale or red, and typically resolve within 24 hours at any given site. It affects approximately 20% of people at some point in their lifetime. Urticaria is classified as acute (lasting under 6 weeks, usually allergic or infection-related) or chronic (persisting beyond 6 weeks, usually spontaneous or physical in trigger). Chronic spontaneous urticaria (CSU) affects 1% of the population and can significantly impair quality of life. Angioedema — deeper swelling of the dermis and subcutaneous tissue, commonly affecting lips, face, and throat — accompanies urticaria in 40% of cases. The burden of chronic urticaria is substantial — affecting work performance, social activities, and mental health — with quality-of-life studies demonstrating that patients with chronic spontaneous urticaria (CSU) experience disease burden comparable to ischaemic heart disease during active phases of illness.

Acute urticaria is most commonly caused by IgE-mediated allergic reactions to foods (nuts, shellfish, eggs, milk), medications (penicillin, NSAIDs, ACE inhibitors), insect stings, or viral infections. In approximately 50% of acute cases no cause is identified. Chronic spontaneous urticaria is autoimmune in 40-50% of cases — autoantibodies against IgE or the high-affinity IgE receptor (FcεRI) on mast cells cause spontaneous histamine release. Physical urticarias are triggered by specific stimuli: cold (cold urticaria), heat, pressure (delayed pressure urticaria), vibration, sunlight (solar urticaria), or water (aquagenic urticaria). NSAIDs worsen CSU in approximately 30% of patients. H. pylori infection, thyroid autoimmunity, and other underlying conditions are associated with CSU in some patients.

Individual urticaria lesions (wheals) are raised, pale or erythematous, clearly demarcated, and intensely pruritic (itchy). Wheals are transient — each individual lesion resolves within 24 hours without leaving marks (distinguishing urticaria from vasculitis and bullous diseases). New wheals continuously appear elsewhere as others resolve. Symptoms are typically worse in the evening and at night. Angioedema causes deeper swelling of the lips, tongue, face, hands, feet, and genitalia — lasting up to 72 hours and causing pain rather than itch. Throat angioedema can threaten the airway. In severe anaphylaxis, urticaria accompanies systemic features: bronchospasm, hypotension, tachycardia, and loss of consciousness. The Urticaria Activity Score 7 (UAS7), a validated patient-reported outcome measure based on daily wheal counts and itch severity recorded over 7 consecutive days, is used to monitor disease activity and guide evidence-based treatment escalation decisions in specialist clinics.

Diagnosis is clinical based on the characteristic appearance and history of wheals resolving within 24 hours. For acute urticaria in suspected IgE-mediated allergy, skin prick tests or specific IgE blood tests (allergen-specific RAST/ImmunoCAP) identify the culprit allergen. For chronic spontaneous urticaria, the EAACI/GA2LEN guidelines recommend a baseline blood panel: full blood count, ESR/CRP, thyroid function and antibodies. Autologous serum skin test or basophil activation test identifies autoimmune CSU. Physical provocation tests (ice cube test for cold urticaria, dermatographometer for symptomatic dermographism) diagnose physical urticarias. Extended investigations for underlying disease are guided by clinical suspicion rather than routinely. Skin biopsy is required only when vasculitis or urticarial bullous pemphigoid is suspected (wheals lasting over 24 hours, painful rather than itchy).

Step 1: Second-generation non-sedating antihistamines (cetirizine 10mg, loratadine 10mg, fexofenadine 180mg, bilastine 20mg, rupatadine 10mg) daily are first-line treatment for both acute and chronic urticaria. Step 2: If standard dose fails after 2-4 weeks, increase to up to 4x the licensed dose of the second-generation antihistamine (EAACI guideline recommendation). Step 3: Add omalizumab (Xolair) 300mg subcutaneous injection every 4 weeks — a biologic anti-IgE monoclonal antibody licensed for antihistamine-refractory CSU. Effective in 70-80% of treatment-resistant cases within 1-3 doses. Step 4: Cyclosporin A 3-5mg/kg/day for omalizumab-non-responders. Short courses of oral prednisolone are used for severe acute urticaria flares only. Avoid NSAIDs and aspirin in CSU patients. Adrenaline auto-injector (EpiPen) is essential for patients with a history of anaphylaxis or severe throat angioedema.

Untreated or inadequately controlled urticaria and angioedema can have serious consequences. Anaphylaxis — the most severe complication — occurs when urticaria is triggered by a potent allergen (food, insect venom, medication) and progresses to systemic cardiovascular and respiratory involvement; delayed epinephrine administration in food-triggered anaphylaxis with urticaria is associated with fatal outcome. Laryngeal angioedema without epinephrine treatment causes complete airway obstruction and asphyxiation — throat angioedema is a life-threatening emergency. Hereditary angioedema (HAE — C1 inhibitor deficiency) causes recurrent attacks of severe angioedema without urticaria, with visceral oedema producing severe abdominal pain mimicking a surgical emergency, and laryngeal oedema with historical mortality of 25-30% before modern treatment. Chronic spontaneous urticaria causes profound quality-of-life impairment comparable to ischaemic heart disease — 40-50% of sufferers develop depression and anxiety, disrupting sleep, social activities, and work performance. Oral decongestant or sedating antihistamine overuse may cause rebound symptoms and cardiovascular side effects. Dermatographism and physical urticarias significantly restrict normal activities such as exercise, outdoor activities, and physical contact.

For IgE-mediated acute urticaria, strict avoidance of the identified allergen (food, medication, insect venom) is essential. Carry an epinephrine auto-injector and wear medical alert identification if you have confirmed anaphylaxis risk. For chronic urticaria, avoid known triggers: NSAIDs, aspirin, alcohol, tight clothing, overheating, and physical triggers. Maintain a symptom diary to identify personal triggers. The Urticaria Activity Score 7 (UAS7) is a validated patient-reported tool for monitoring disease activity and treatment response — used to guide step-up or step-down therapy. Aim for UAS7 below 6 (well-controlled). For CSU, regular reassessment every 3-6 months to check for spontaneous remission (50% achieve remission at 1 year, 80% at 5 years).

Seek emergency care immediately (call ambulance) for urticaria accompanied by difficulty breathing, throat swelling, stridor, hoarseness, dizziness, rapid heartbeat, or collapse — these are signs of anaphylaxis requiring immediate epinephrine. Go to the emergency department urgently for rapidly spreading angioedema affecting the face, lips, or throat even without breathing difficulty. See a doctor promptly if acute hives fail to settle within a few days, wheals last longer than 24 hours, or symptoms severely disrupt daily life. Consult an allergist or dermatologist for urticaria persisting beyond 6 weeks (chronic urticaria), to confirm the diagnosis, investigate for underlying causes, and optimize treatment with antihistamine up-dosing or omalizumab.