Urticaria Flashcards
What is urticaria also known as?
Hives
What is urticaria?
A skin rash with red, raised, itchy bumps
What are the timescales of urticaria?
Acute or chronic
When does urticaria become chronic?
When it lasts over 6 weeks
Is chronic urticaria common in children?
No, its rare
What is the underlying cause of acute urticaria?
IgE mediated type-I hypersensitivity reaction
What causes the skin lesion of urticaria?
Inflammatory reaction in the skin leading to leaky capillaries in the dermis resulting in oedema
How doe the oedema of urticaria subside?
When the interstitial fluid is absorbed into the surrounding cells
What are the causes of urticaria?
- Idiopathic
- Infections
- Dietary
- Drugs
- Plants
- Hereditary
- Urticarial vasculitis
- Physical urticarial
- Autoimmune
What are some dietary causes of urticaria?
- Fish
- Shellfish
- Nuts
- Eggs
What drugs can cause urticaria?
- Penicillin
- Aspirin
- NSAIDs
- ACE inhibitors
What can cause physical urticaria?
- Water contact
- Exercise induced
- Vibratory
- Cold contact
What autoimmune condition can cause urticaria?
SLE
What are the risk factors for urticaria?
- Hay fever
- Asthma
What is acute urticaria characterised by?
Short-lived, itchy wheals, angioedema or both
How long do the wheals last in acute urticaria?
2-24 hours depending on cause
What investigations are required in acute urticaria?
None
What tests may be require in severe, chronic urticaria?
- FBC
- ESR
- TFT
- ANA
- LFT
- IgE
- Allergy testing
- Physical challenge
What are the differentials of urticaria?
- Drug eruptions
- Stevens-Johnson syndrome
- Erythema multiforme
How can urticaria be managed?
- Avoid trigger
- Non-sedating antihistamine
- Menthol 1% in aqeuos cream to sooth itch
When may short-term prednisolone be indicated?
If child remains symptomatic on maximal antihistamine dose
What other medications may be useful?
- H2 blocker
- Anti-leukotrienes
- Adrenaline
When should a referral to dermatologist be made?
- Severe acute urticaria
- Failure of treatment
- Chronic urticaria lasting > 6 weeks
