Allergenicity of Opioid Analgesic Drugs

Many of the symptoms elicited by histamine are the same or similar to those of antibody-mediated type I allergic responses and some other 

One might assume that given the widespread prescribing and frequent administration as analgesics of morphine, codeine, their hydro- and oxy-derivatives, meperidine, fentanyl, and tramadol, and the use of heroin (often by intravenous injection) and methadone by addicts, IgE-antibody-mediated allergy to these drugs would not be uncommon. This is not the case. The reasons why are examined below. 

At normal doses, codeine, even more so than morphine and despite its capacity to release histamine in the skin (but perhaps also reflecting the differences in parenteral administration), has rarely been implicated in anaphylactoid or anaphylactic reactions. However, an unusual case of fever with urticaria, generalized pruritus, and 

Inhibition (%) of IgE antibody Compound Structure binding to morphine-Sepharose with 200 nmoi of compound 

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