Severe histamine mediated reactions to intravenous drugs used in anaesthesia.

Severe histamine mediated reactions to intravenous drugs used in anaesthesia may occur as a result of anaphylactic and anaphylactoid reactions. The incidence is rare, but appears to be increasing. The difficulties in diagnosing such reactions and in determining the drug responsible and how these difficulties have led to confusion in the literature are discussed. Six cases of severe histamine mediated reactions are presented and detailed analyses of the drugs in these and other reported reactions is made showing varied clinical patterns with different drugs. The prevention, treatment, and follow-up of severe histamine mediated reactions are considered.