Promethazine MAOIs

One early reviewer stated that MAOIs increase the potency of phenothi-azine derivatives such that their initial dose should be reduced by three-quarters. He briefly mentions a case of a patient taking long-term perphenazine who developed a Parkinson-like syndrome with extrapyrami-dal symptoms a few hours after starting an MAOI. The US manufacturers note that, based on the increased incidence of extrapyram-idal effects reported with concurrent use of some MAOIs and phenothiazines, this possibility should be considered with promethazine."... 

A single report describes a woman taking an MAOI who developed a severe occipital headache after taking 30 mL of a paediatric cough linctus. Initially this interaction was attributed to promethazine, but it is now known that the linctus in question contained phenylpropanolamine, which is much more likely to have been the cause. See N OIs or RIMAs + Sympathomimetics Indirectly-acting , p.ll47 for the interaction with phenylpropanolamine. 

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