Morphine is a mu opioid agonist - one adverse effect of opioids is mast cell degranulation that is IgE-independent. Release of histamine is akin to an anaphylactic reaction --> pruritis, etc.
(From UW 11852) Some medications including opioids, radiocontrast dyes, and some antibiotics (e.g. vancomycin) can induce and IgE-INDEPENDENT mast cell degranulation by activation of protein kinase A and PI3 kinase, which results in release of histamine, bradykinin, and other chemotactic factors -> diffuse itching, pain, bronchospasm, and localized swee=lling (urticaria).
Is this just red-man syndrome?
Direct mast-cell degranulation caused by vancomycin....and also morphine?