What are the key steps in assessing a patient with a suspected drug allergy in primary care?

When assessing a patient with a suspected drug allergy in primary care, the key steps are:

• Take a detailed history and perform a clinical examination, focusing on the timing, nature, and pattern of the reaction, including immediate (within 1 hour) and non-immediate reactions (hours to weeks after exposure) as described in the NICE guideline tables of allergic patterns and timing of onset.
• Consider whether the reaction is likely caused by drug allergy by evaluating if the drug is known to cause the reaction type, if the patient had a similar previous reaction, and by excluding non-drug causes or symptoms limited to the gastrointestinal system.
• In cases of suspected anaphylaxis, take blood samples for mast cell tryptase to support diagnosis, following NICE anaphylaxis guidelines.
• Consider stopping the suspected drug and advise the patient to avoid it in the future, while managing acute symptoms as needed and referring severe reactions to hospital.
• Document the suspected drug allergy clearly in the patient’s medical records and provide the patient with structured written information about the suspected allergy and drugs to avoid.
• Refer to a specialist drug allergy service if the patient has had a suspected anaphylactic reaction or a severe non-immediate cutaneous reaction (e.g., DRESS, Stevens–Johnson syndrome, toxic epidermal necrolysis).

These steps ensure a thorough assessment and appropriate management of suspected drug allergy in primary care.