Urticaria Flashcards
What is cutoff for acute vs chronic urticaria?
6 weeks
What are the general types of triggers for acute urticaria?
- Bugs: insects or infections
- Drugs: ACEI and NSAIDs, opiods
- Physical: dermatographism, cold, delayed pressure, cholinergic, adrenergic, heat, solar, aquagenic, vibrational
- Foods: Wheat, eggs, milk, peanuts, soy (WEMPS)
Patient with cold induced urticaria, what do you need to counsel on?
don’t swim alone, can get massive histamine release→ hypotension, syncope, drowning
Most common infection causing acute urticaria?
URI
most common drugs causing urticaria?
- ACEI
- NSAIDs
- Opiods
What are the three most important things to ask a patient who presents with urticaria?
- any signs of angioedema/anaphylaxis (SOB, difficulty breathing, swelling of lips or throat)
- Duration of lesion: Ask about urticarial vasculitis (>24 hours, burning/pain as opposed to itching)
- Review of systems
Histology of Urticaria?
- limited epidermal change
- superficial dermal edema
- perivascular and interstitial mixed infiltrate with neuts
- vascular damage if urticarial vasculitis
Questions to ask when taking history of urticaria?
- any signs of angioedema/anaphylaxis?
- Duration of lesions
- Triggers: recent illness? Bug bites, physical, foods (WEMPS)
Treatment for Urticaria:
- Avoid triggers (NSAIDS, aspirin, WEMPS foods, stress, alcohol)
- 2nd gen antihistamines (can increase dose if not working, can also add another 2nd gen anti-histamine)
- anti itch creams with pramoxine
Duration of urticarias by cause:
- Spontaneous urticaria, delayed pressure urticaria: 2-24 hours
- Contact urticaria (latex allergy): less than 2 hours
- Physical urticaria (heat, cold, water, ultraviolet light): less than 1 hour
- Urticarial vasculitis: 1-7 days
- Angioedema: 2-3 days
Doses for 2nd gen antihistamines in urticaria? How high can you go?
Cetirizine and loratadine are 10mg twice daily
- can go up to 4 fold higher!
- can also add sedating antihistamine like hydroxyzine at bedtime
Should urticaria be treated with antihistamines as needed, or daily?
Daily
What is the prognosis of acute urticaria? Chronic?
Acute: most resolve spontaneously within 6 weeks
- chronic: often resolve within 6 months, but after that is unclear of the course with up to 20% having symptoms for 20 years
- (remember 6 weeks and 6 months respectively)
What medication is approved for chronic urticaria that failed antihistamine tx?
Omalizumab
30% rule for chronic urticaria:
- 30% a/w autoantibodies to mast cells receptor or IgE itself
- 30% of pt’s have thyroid auto-ab
- 30% exacerbated by aspirin
- 30% resolve within 5 years
