Urticaria and angioedema
Cards (10)
- Urticaria:
- Characterised by very itchy wheals (hives), with or without surrounding erythematous flares
- A wheal is a superficial skin coloured or pale skin swelling, usually surrounded by erythema that lasts anything from a few minutes to 24 hours
- Urticaria can co-exist with angioedema:
- Deeper swelling within the skin or mucous membranes
- Commonly affects the face (especially eyelids and perioral sites), hands, feet, and genitalia
- May involve the tongue, uvula, soft palate or larynx
- Acute urticaria = symptoms for less than 6 weeks
- Chronic urticaria:
- Symptoms for more than 6 weeks
- Chronic spontaneous = no known trigger
- Chronic inducible = known trigger
- Wheals usually take longer to appear after contact with trigger
- Wheals pathophysiology:
- Due to release of chemical mediators (including histamine) from tissue mast cells and circulating basophils
- The mediators activate sensory nerves and cause dilation of blood vessels and leakage of fluid into surrounding tissues
- Bradykinin release causes angioedema
- Acute causes:
- Acute viral or bacterial infection
- Food or drug allergy - IgE mediated
- Bee or wasp stings
- Contact urticaria e.g. latex
- Chronic causes:
- Mainly idiopathic
- about half of patients carry functional IgG autoantibodies to IgE
- Has also been associated with chronic underlying infection and chronic autoimmune disease
- Wheals may be aggravated by:
- Heat
- Viral infection
- Tight clothing
- NSAIDs are associated with chronic urticaria
- Management:
- Identify and manage any triggers
- Cool affected area with a fan, cold flannel, ice pack
- For people with symptoms requiring treatment = second-generation H1 antihistamine e.g. cetirizine or loratadine
- If symptoms are severe also give short course of oral corticosteroid
- Can prescribe antihistamine for 3-6 months or prophylactically depending on frequency of symptoms
- Refer to dermatology if no improvement within 4 weeks