Drug allergy work-up

Introduction

It makes it possible to confirm or rule out a true allergy, to avoid needlessly excluding medicines and to make all future prescriptions safer (doctors, emergency departments, hospital, dental and aesthetic treatments).

When should a work-up be done?

A work-up is indicated in the following situations:

• A skin or generalised reaction after taking a medicine
• Uncertainty between allergy, intolerance or side effect
• A history of severe reaction (generalised urticaria, angio-oedema, anaphylaxis)
• A long-standing ‘allergy’ label without formal proof
• A medical need to use a suspected medicine again

👉 The work-up is ideally carried out some time after the acute episode (usually several weeks later).

Steps of the work-up

1. Detailed medical history

• Review of the medicine taken (active substance, dose, route)
• Timeline (interval between taking the medicine and the symptoms)
• Precise description of the symptoms

2. Analysis of the reaction

• Classification (immediate or delayed)
• Assessment of severity
• Identification of the priority substances to test

3. Specialist allergy tests

Depending on the clinical picture:

• Immediate-reading skin tests (skin prick tests, intradermal tests)
• Drug patch tests (for delayed reactions)
• Targeted laboratory tests
• Controlled provocation tests (if indicated, in a safe setting)

Interpretation and results

At the end of the work-up, the allergist establishes:

• Formal confirmation or exclusion of the allergy
• Precise identification of the substance or substances to avoid
• Assessment of the risk of cross-reactions
• Identification of safe alternative medicines

Documents provided

You receive a complete file for your safety:

• An official allergy report
• A clear list of contraindicated medicines
• A list of permitted alternatives
• A drug allergy card to show to healthcare professionals