On this page
Referral and warning signs
When to refer
Refer Urgently if: Anaphylaxis or angioedema involving airway. Refer to Specialist (Dermatologist/Allergist) if: Chronic urticaria (>6 weeks). Urticaria unresponsive to standard antihistamine doses. Suspected urticarial vasculitis. Need for investigation of underlying cause or advanced therapies.
Red flags
- Signs of anaphylaxis (difficulty breathing, wheeze, hypotension, collapse).
- Angioedema of tongue, throat, larynx.
- Wheals lasting >24 hours, painful, or leaving bruises (suggests vasculitis).
- Associated systemic symptoms (fever, joint pain - suggests systemic cause).
Signs and symptoms
- Wheals: Raised, erythematous or pale, oedematous plaques with well-defined borders. Often intensely itchy (pruritic). Individual lesions typically last <24 hours and resolve without scarring, but new lesions appear.
- Angioedema: Deeper dermal/subcutaneous swelling, often affecting face, lips, tongue, throat, extremities, genitalia. May be non-itchy, can be painful or cause sensation of tightness. Can be life-threatening if airway involved.
- Papular Urticaria: Persistent itchy papules, often grouped, typically at sites of insect bites (common in children).
Risk factors
- Acute Urticaria: Infections (viral URTI common trigger, bacterial, parasitic), Medications (penicillins, NSAIDs, ACE inhibitors), Foods (nuts, eggs, shellfish, milk), Insect bites/stings, Latex allergy, Physical stimuli (dermographism, cold, heat, pressure, vibration, solar, water), Idiopathic.
- Chronic Spontaneous Urticaria (CSU): Often idiopathic (autoimmune basis suspected in many). Can be associated with thyroid disease, infections.
- Chronic Inducible Urticaria (CINDU): Triggered by specific physical stimuli (as above).
Diagnosis
Clinical assessment
Diagnosis based on history of transient, itchy wheals +/- angioedema. Identify potential triggers (foods, drugs, infections, physical stimuli). Duration differentiates acute vs chronic.
Differential diagnosis
- Insect bites (papular urticaria).
- Scabies (itchy papules, burrows, different distribution).
- Eczema (less transient lesions, different morphology).
- Drug eruptions (morbilliform, fixed, etc.).
- Erythema multiforme (target lesions).
- Vasculitis (urticarial vasculitis - lesions last >24h, may be painful/bruised, leave pigmentation).
- Mastocytosis.
Investigations
- Usually not needed for acute urticaria unless anaphylaxis suspected.
- Chronic Urticaria: Consider FBC, ESR/CRP, Thyroid function tests (TSH, anti-TPO), Autoimmune screen (ANA) if suspected. Allergy testing rarely helpful for Chronic Spontaneous Urticaria, may be useful for specific inducible types or food/drug triggers in acute cases.
Diagnostic criteria
Clinical history and appearance of characteristic transient wheals +/- angioedema.
Management
Non-pharmacological management
- Identify and avoid triggers if possible.
- Cool compresses, soothing lotions (e.g., calamine).
- Avoid aggravating factors (heat, alcohol, tight clothing).
Pharmacological treatment
- Antihistamines (H1 Blockers): Mainstay of treatment.
- - Second Generation (Non/Less Sedating): Preferred. (e.g., Cetirizine 10mg OD, Loratadine 10mg OD, Fexofenadine). May need higher doses (up to 4x standard) for chronic urticaria under specialist guidance. (LOC: HC2+)
- - First Generation (Sedating): (e.g., Chlorphenamine 4mg Q4-8H, Promethazine 25mg nocte/BID). Useful if sedation desired (e.g., nighttime itching). (LOC: HC2)
- Systemic Corticosteroids:
- - Short course (e.g., Prednisolone 0.5-1mg/kg, max 40-60mg daily, for 3-7 days) for severe acute urticaria or exacerbations of chronic urticaria. Avoid long-term use. (LOC: HC3/4)
- Anaphylaxis / Severe Angioedema with Airway Compromise:
- - Adrenaline (Epinephrine) IM. (See Emergencies Chapter).
- - Oxygen, IV fluids, IV antihistamines, IV corticosteroids.
- Chronic Urticaria (Specialist Management):
- - High-dose second-gen antihistamines.
- - Add-on therapies: Omalizumab (anti-IgE), Ciclosporin, Montelukast.
- Papular Urticaria: Treat itching (antihistamines, topical steroids), treat secondary infection, insect repellent use.
Monitoring
Monitor symptom control. Assess frequency/severity of flares. Adjust antihistamine dose as needed. Monitor side effects.
Complications
- Angioedema (potentially life-threatening if airway involved).
- Anaphylaxis.
- Impact on quality of life (itching, sleep disturbance).
- Secondary skin infection (from scratching).
Prevention
- Avoid known triggers.
- Regular antihistamine use for chronic urticaria.
- Insect repellents for papular urticaria.
Patient education
- Explanation of urticaria/hives.
- Identification and avoidance of triggers.
- Role of antihistamines (regular use for chronic).
- How to manage acute flares.
- Signs of severe reaction (angioedema/anaphylaxis) requiring emergency care.
- Use of adrenaline auto-injector if prescribed for anaphylaxis risk.
Uganda-specific notes
Common condition. Identifying triggers can be difficult. Second-generation antihistamines preferred if available due to less sedation. Chlorphenamine widely available. Short course oral steroids used for severe flares.
References
- Uganda Clinical Guidelines (UCG) 2023
Chapter 22, Section 22.5.2