What steps should I take to assess a patient presenting with suspected

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

When assessing a patient presenting with suspected adverse drug reactions (ADRs), the appropriate steps include:

Take a detailed history and perform a clinical examination to identify the timing, nature, and pattern of the reaction in relation to drug exposure, considering immediate and non-immediate reactions as described in clinical tables of allergic patterns (e.g., anaphylaxis, urticaria, fixed drug eruptions, DRESS, Stevens–Johnson syndrome) .
Evaluate the temporal relationship between drug administration and onset of symptoms, noting that reactions occurring during or after drug use and consistent with known drug allergy patterns are more likely to be caused by the drug .
Consider previous similar reactions to the same drug or drug class, which increases the likelihood of drug allergy .
Exclude alternative non-drug causes for the symptoms, especially if gastrointestinal symptoms are isolated or if similar symptoms have occurred without drug exposure .
In cases of suspected anaphylaxis, measure serum mast cell tryptase by taking two blood samples as per anaphylaxis guidelines to support diagnosis .
Involve a pharmacist with relevant clinical knowledge when making decisions about medicines use or care pathways involving medicines .
Encourage open, person-centred communication to involve the patient in discussions and decisions about their care, ensuring informed consent and shared decision-making ,.
Report and document the suspected ADR through local and national patient safety incident systems to support learning and prevent harm .

What steps should I take to assess a patient presenting with suspected adverse drug reactions?