Urticaria

  • Urticaria and angioedema are closely related, share many causes and treatments and can coexist
  • They are both manifestations of mast cell degranulation in superficial or deep skin layers respectively. They are not usually due to allergies

Aetiology:

  • 50% of cases of spontaneous urticaria are idiopathic, the other 50% are autoimmune in nature and often have associated thyroid autoantibodies
  • Although spontaneous urticaria is not an allergy, symptoms can be exacerbated by a number of factors such as heat, stress, various medications such as aspirin and other NSAID, and in some cases pseudoallergens
Referral Criteria:
  • Diagnostic uncertainty (e.g. suspected drug rash or vasculitis)
  • Severe disease unresponsive to primary care management (secondary care treatments include cyclosporine, oral steroids and omalzumab)
Formulary, Chapter 13. Skin: Management of urticaria

Assessment

Signs and Symptoms

  • A slight female predominance
  • Can affect any age although 50% present between the ages of 20 and 40
  • 25% of patients have an atopic background
  • Symptoms:
    • Although the condition may persist for several months, or in some cases years, individual lesions generally last between 30 minutes and 4 hours
    • Can have additional elements of physical urticaria such as dermographism or delayed pressure urticaria
  • Angioedema will affect some patients but is rarely life threatening
  • Natural history - 50% of patients with spontaneous urticaria can expect to be clear in six months, but some persist for years
  • Rapid appearance of raised erythematous very itchy skin swellings "wheals"

Differential Diagnoses

Individual lesions disappear within 24 hours and if not consider:

  • erythema multiforme
  • urticarial vasculitis (lesions can last for days and leave bruising)
  • erysipelas
  • if female of child bearing age - polymorphic eruption of pregnancy

Acute urticarial

  • Idiopathic
  • Viral infections
  • Physical – touch, pressure, hot, cold, solar, water, chemicals, cosmetics
  • Drugs – aspirin, opioids, NSAIDs, antibiotics, ACE inhibitors, statins, diuretics
  • Allergic – foods, infections

Chronic urticaria

  • Idiopathic most common
    • Chronic idiopathic urticaria is not an allergy but more because of irritable mast cells that degranulate with little or no provocation
    • Often in 20-40y old females
    • Often a response to emotional stress or hormonal changes
    • Usually burns out after several months to a couple of years
  • Physical – touch, pressure, hot, cold, solar, water
  • Drugs – aspirin, opioids, NSAIDs, antibiotics, ACE inhibitors, statins, diuretics
  • Allergic – foods, infections Secondary to other disease – SLE, viral hepatitis, hyperthyroidism, lymphoma, infection
  • Auto-immune urticaria

Investigations

  • Blood tests
    • Check thyroid function tests (TFT) and autoantibodies - patients found to have significant titres of thyroid autoantibodies should have their TFT re-checked every six months as they are at increased risk of developing thyroid disease
  • H.pylori status
    • Check in patients with recalcitrant urticaria and who also have dyspepsia - urticaria may improve in some patients following H.pylori eradication
  • Other tests
    • In general, patients will not benefit from radioallergosorbent test (RAST) or skin prick tests as an allergic cause is highly unlikely - a RAST test against a specific food may sometimes be used to disprove a theory, such that a negative result would make it very unlikely that any given food is responsible for the reaction
  • There is no place for patch testing

Referral

Referral criteria

  • Diagnostic uncertainty (e.g. suspected drug rash or vasculitis)
  • Severe disease unresponsive to primary care management (secondary care treatments include cyclosporine, oral steroids and omalzumab)

Referral instructions

e-Referral Service selection:

  • Specialty: Dermatology
  • Clinic Type: Not Otherwise Specified
  • Service: DRSS-Western-Dermatology-Devon CCG-15N

Referral forms

DRSS Referral form

Supporting Information

Patient Information

Evidence

South and West Devon - formulary - Skin

The Primary Care Dermatology Society

Pathway Group

This guideline has been signed off by the Western Locality on behalf of NHS Devon CCG.

Publication date: 30 January 2017

 

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