This guideline covers diagnosing and managing drug allergy in all age groups. It aims to make it easier for professionals to tell when someone is having an allergic reaction, by specifying the key signs and patterns to look out for. It also makes recommendations on improving people’s understanding of their drug allergies, and ensuring these are recorded properly in their medical records.
All drugs have the potential to cause side effects, also known as 'adverse drug reactions', but not all of these are allergic in nature. Other reactions are idiosyncratic, pseudo-allergic or caused by drug intolerance. The British Society for Allergy and Clinical Immunology (BSACI) defines drug allergy as an adverse drug reaction with an established immunological mechanism. The mechanism at presentation may not be apparent from the clinical history and it cannot always be established whether a drug reaction is allergic or non-allergic without investigation. Therefore, this guideline has defined drug allergy as any reaction caused by a drug with clinical features compatible with an immunological mechanism.