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Dermatology (Skin Conditions)

Urticaria

A common skin condition characterized by the sudden appearance of transient, itchy, raised wheals (hives) resulting from mast cell degranulation and histamine release in the dermis. Can be acute (<6 weeks) or chronic (>=6 weeks). Papular urticaria involves more persistent papules, often from insect bites.

Also known as: Hives, Nettle Rash, Wheals

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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

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