KISS: Allergy Testing in Primary Care

BSACI Primary Care Guideline 2025

Background/key principles:

• References to ‘allergy’ in this guideline refer to immediate/type 1 (IgE-mediated) hypersensitivity reactions.
• Symptoms occur within minutes/max 1 hour of exposure and include:
  • Rash (urticaria, angioedema or erythema), wheeze, hypotension, vomiting and diarrhoea.
• Symptoms are REPRODUCIBLE and occur with EVERY subsequent exposure and do NOT occur without exposure to the allergen.
• Allergy is a CLINICAL diagnosis, and testing should be strictly guided by the clinical history, with tests limited to relevant triggers only; ‘Screening’ allergy testing is not indicated.

Assessment:

• History is KEY - Use the STAR principles:
  • Are Symptoms consistent with an IgE-mediated mechanism?
  • Is Timing consistent with an IgE-mediated mechanism?
  • Can symptoms be attributed to a likely Allergen?
  • Are symptoms Reproducible?
• IgE testing should only be undertaken if the answer is ‘yes’ to ALL 4 of the STAR questions above.
• In most cases, it is rarely necessary to test for more than 5 individual allergy-specific IgEs.

General guidance for allergy testing:

• Measurement of total IgE is not helpful in allergy testing.
• Food testing:
  • Do not use bundles of tests, e.g. food mixes - test only the specific food compatible with the allergy.
  • Any suspected food that has been consumed and tolerated after the event can be excluded without testing.
  • Isolated delayed (>1 hour) GI features are generally not consistent with allergy.
• Inhalant allergies:
  • Always consider non-allergic respiratory disease, including perennial rhinitis, before considering allergy/testing.
  • Timing and duration of symptoms can help identify allergens (click here for a seasonal guide to allergy patterns).
  • Only test if it will change management:
    • If an allergen can't be avoided (e.g. a pollen), testing may not be helpful, but if avoidance is possible (e.g. testing for dog dander), then it probably is helpful.
    • This would include testing if required by local pathways prior to referral to either ENT or allergy clinics.
• Drug allergies - do not test in primary care; refer to allergy services as per NICE guidance if:
  • Severe reaction, e.g. anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis, severe angioedema or asthmatic reaction.
  • Suspected antibiotic allergy and likely to need that antibiotic in the future, especially beta-lactam antibiotics.
• Bee and wasp venom:
  • Do not test for local reactions, even if large.
  • If systemic features are present, refer to the allergy clinic; consider baseline mast cell tryptase and IgE wasp and bee venom levels at the point of referral.

Referral:

• If referring to an allergy clinic, check your local referral guidelines, but information to include in referral:
  • History based on STAR assessment above.
  • Examination findings at the time of the acute event (if available), e.g. RR, pulse, BP.
  • Treatments given and response.
  • Also consider mast cell tryptase levels.