Title: Hypersensitivity to excipients

Abstract

Excipients are considered inert substances, without an active role in treatment, added to drugs in order to change their solubility or their kinetics of absorption, increase the stability, influence palatability or create a distinctive appearance. The hypersensitivity reactions to excipients are rare, but they can be severe. An accurate diagnosis, even sometimes is a real challenge, is mandatory. In its absence, the imputability of the reaction can be inappropriately attributed to the active substance leading to the useless eviction of it and the persistence of the exposure to the culprit with risk of recurrence. Their clinical presentation is heterogenous, including immediate (from urticaria / angioedema to anaphylaxis) and delayed hypersensitivity reactions. A suspicion of hypersensitivity to excipients appears in case of multiple drug hypersensitivity. The diagnosis is based on clinical history and an allergy workup including skin tests (skin prick-tests, intradermal tests, patch-tests), biological tests when available (basophil activation tests, specific IgE) and, in selected cases, provocation tests. The list of excipients must be accessible for all drugs. The healthcare providers must be aware of the possibility of a hypersensitivity reaction to them.