Anaphylaxis to muscle relaxants: cross sensitivity between relaxants

Two patients are described who had clinical anaphylaxis due to muscle relaxants. One patient had systemic hypersensitivity and positive intradermal tests to d-tubocurarine and alcuronium. The second had systemic hypersensitivity to d-tubocurarine and positive intradermal tests to d-tubocurarine, alcuronium, and pancuronium. It is suggested that positive intradermal tests to more than one relaxant may mean allergy to more than one relaxant rather than false positive test. Cross sensitivity between alcuronium and d-tubocurarine occurs and a similar situation may exist for suxamethonium and gallamine. When intradermal testing is carried out after anaesthetic reactions all relaxants should be tested.