Urticaria Flashcards
Define urticaria
Superficial swelling of the skin (epidermis and mucous membranes) that result in a red (initially with a pale centre), raised, and intensely itchy rash
What is the difference between acute and chronic urticaria
Acute urticaria = symptoms < 6 weeks
Chronic urticaria = symptoms > 6 weeks
What are the causes of acute urticaria
Spontaneous, idiopathic
Acute viral infection
Allergic reaction: foods, insect bites, contact allergens, drugs (penicillin, aspirin, NSAIDs, vaccinations)
What are the causes of chronic urticaria
Chronic spontaneous urticaria (CSU)
Autoimmune urticaria
Chronic inducible: aquagenic, cholinergic, cold, heat, symptomatic dermatographism, delayed pressure, solar, contact
IgE mediated reaction
Viral infection
What are the symptoms of urticaria
Hives
Itchy
Arise shortly after exposure to the potential allergen (<1 hour)
Reproducible
(1) A central swelling of variable size (red or white in colour), almost invariably surrounded by an area of redness (flare).
(2) Associated itching or burning)
(3) Skin returns to normal within 1-24 hours
Redness to skin
What are the differentials for urticaria
Atopic eczema
Contact dermatitis
Chronic pruritus
Erythema multiforme
Insect bite or sting
Polymorphic eruption of pregnancy
What are the signs of urticaria on examination
Urticaria
- Weals that vary in size (mm to hand-sized)
- Single or numerous, localised or generalised
- A central swelling of variable size (red or white in colour), almost invariably surrounded by an area of redness (flare)
investigations for urticaria
Clinical diagnosis, investigations done if there is no obvious cause
Bloods: TFTs, CRP/ESR, FBC
Other: skin prick testing, skin biopsy
What is the management for urticaria
- Assess severity - Urticaria Activity Score (UAS7)
Records severity of itching + no. of weals for 7 days
<7 in 1 week = control
>28 in 1 week = severe disease - Identify any potential triggers e.g. with symptom diary
- arrange investigations if trigger cannot be found
What is the management for mild urticaria
Supportive - Likely to be self-limiting without treatment
What is the management for moderate urticaria
First line: Non-sedating anti-histamines (second gen) - Cetirizine for up to 6 weeks
Second line: oral corticosteroid e.g. prednisolone
+ follow up
What is the management for severe urticaria
Non-sedating anti-histamines (second gen) - Cetirizine for up to 6 weeks + oral corticosteroid e.g. prednisolone
Contact dermatology
Refractory: omalizumab (anti-IgE antibody)
+ follow up
+ consider psychology referral
What are the complications of urticaria
Progression to angioedema and anaphylaxis, Airway obstruction
Skin infection — due to extensive itching and subsequent excoriation.
Scarring — uncontrolled excoriation can lead to scarring.
Poor sleep — due to itching.
Social isolation and embarrassment.
Reduced performance at work or school.
Anxiety and depression.
Reduced quality of life
What is the prognosis for urticaria
Excellent prognosis, normally self-limiting and short-lived
Most react well to the allocated treatment
50% of people with CSU go into remission after 6 months-5 years