Introduction
Urticaria And Angioedema is an eruption of evanescent wheals or hives which can result from many different stimuli on an immunologic or non-immunologic basis.
The most common immunologic mechanism is hypersensitivity mediated by IgE.
Another mechanism involves activation of the complement cascade.
The activation of cutaneous mast cells and their release of mediators is the unifying feature of most urticaria.
Mast cells are found in the immediate vicinity of blood vessels.
They release preformed mediators
(histamine, heparin and various
enzymes) as well newly manufactured
ones (prostaglandins, leukotrienes).
A hive or urticarial lesion is the result of
localized oedema in the dermis.
Causes of urticaria and angioedema
- Medications
- Food
- Aero-allergens
- Latex; seminal fluid (contact urticaria)
- Insect antigens (bees, wasps or hornet toxins)
- Infections and infestations (parasitic, fungal,
- Bacterial and viral)
- Foreign proteins (antisera, vaccinations)
- Physical stimuli (pressure, heat, cold, cholinergic stimuli, water, light and irradiations)
- Auto-immune disorders, enzyme defects (C1 esterase inhibitor deficiency)
- Psychosocial conflicts (stress, depression)
- Excessive mast cells (mastocytoma, urticaria pigmentosa)
- Pseudoallergy (mast cell degranulators e.g.
- NSAIDS; dyes, preservatives, contact urticaria)
- Serum sickness
- Malignancies
- Idiopathic
Symptoms and clinical features of urticaria and angioedema
Symptoms of urticaria and angioedema may be acute or chronic:
Acute urticaria is of sudden onset and lasts less than 6 weeks.
Chronic urticaria persists for more than 6 weeks with either:
- Daily emergence of new wheals (chronic continuous) or
- Occasional hive-free periods (chronic recurrent)
The typical urticarial reaction is similar to the triple response of Lewis
- Initial erythema
- Next oedema (the hive)
- Finally an erythematous ring surrounding the hive
Urticarial lesions may:
- Vary in size and shape over minutes to hours
- Present an orange-skin appearance
- -Become bullous
The pruritus associated with urticaria is usually extreme.
Excoriations are extremely unusual because the lesions are almost invariably rubbed, not scratched.
Dermographism is characterized by wheal and erythema after minor stroking of, or pressure on the skin
- It is commonly found under pressure areas e.g. the belt line
May persist for years, but spontaneous
regression usually occurs within 2 years.
Angioedema is the involvement of deeper vessels
- Characterized by painless, deep, subcutaneous swelling
- Often involves periorbital, circumoral and facial regions; palms, soles and the genitalia
- May target the gastrointestinal and
respiratory tracts, causing abdominal pain, coryza, asthma and respiratory problems - Respiratory tract involvement may cause airway obstruction
- Anaphylaxis and hypotension may also occur
Differential diagnoses
- Gyrate erythemas
- Urticarial vasculitis
- Mastocytosis
- Pityriasis rosea (early lesions)
- Bullous lesions:
- Pemphygus
- Pemphygoid
- Erythema multiforme
- Fixed drug eruption
- Angioedema:
- “Calabar swelling”
- Cellulitis
- Idiopathic scrotal oedema of children
- Melkerson-Rosenthal syndrome
- Cold urticaria:
- Cryoglobulinemia Immune complex diseases
- Systemic lupus erythematosus and other collagen vascular diseases
- Macroglobulinemia
- Mycoplasma infections (cold hemagglutinins)
- Syphilis
- Familial cold urticaria
- Acquired cold urticaria
Complications of urticaria and angioedema
- Emotional distress in chronic cases
- Fatality
Investigations
- Suggested by meticulous history and physical examination
Treatment objectives
- To alleviate symptoms
- Eliminate and treat cause
Drug treatment
Chlorpheniramine maleate
- Adult: 4 mg orally every 4 – 6 hours
(maximum 24 mg daily) - Child:
- under 1 year, not recommended 1
- 2years: 1mg every 12 hours;
- 2-5years 1mg every 4 to 6 hours (maximum 6 mg daily);
- 6 – 12: years: 2 mg every 4 -6hours (maximum 12 mg daily)
If less sedation is required (e.g. day time)
Or:
Loratadine
- Adult and Child over 6 years: 10 mg orally daily
- Child 2-5years5mgdaily
If persistent and chronic urticaria
Add Doxepin (oral form discontinued)
- Adult: apply thinly 3 – 4 times daily; usual maximum 3g per application (total daily maximum 12 g)
- Child: not recommended for children under 12 years
Or:
(For symptomatic dermographism and
chronic urticaria)
Add:
Ranitidine hydrochloride
- Adult: 150 mg orally every 12 hours or 300 mg at night
Not to be used alone for the treatment of urticaria
Refractory cases
Systemic corticosteroids
Prednisolone: 0.5 to 1.0 mg/kg orally daily
Adjuvant measures
- To relieve itching: Tepid or cold tub baths or showers
- Add starch, or sodium bicarbonate, menthol, or magnesium sulfate to bath water
- Do not scrub the body with sponge (it promotes degranulation of cutaneous mast cells)
- Avoid medicines likely to cause urticaria/angioedema
- Eliminate any suspected food
- Counselling
Notable adverse drug reactions, caution and contraindications
Chlorpheniramine maleate:
- Patients not to drive or operate machinery
Ranitidine:
- Tachycardia, agitation, visual disturbances, alopecia, gynaecomastia and impotence
- Caution in hepatic impairment, pregnancy and in breast feeding
loratadine:
- Headache, dry mouth, drowsiness, dizziness and nausea
- Caution in the elderly especially if renal
function is compromised
Doxepin:
- Caution in cardiac disease
- Contraindicated in recent myocardial infarction, arrhythmias, glaucoma and severe liver disease
- May cause dry mouth, sedation, blurred vision, constipation, nausea, difficulty with
micturition
Prevention
- Eliminate/avoid any identified/possible causal factor(s).