Methylene blue and Promethazine and dextromethorphan interaction
Methylene blue and Promethazine and dextromethorphan: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Promethazine and dextromethorphan (Promethazine Hydrochloride and Dextromethorphan Hydrobromide) label · effective 2025-08-08
Dextromethorphan should not be used in patients receiving a monoamine oxidase inhibitor (see PRECAUTIONS – Drug Interactions ).
Drug Interactions Monoamine Oxidase (MAO) Inhibitors – Hyperpyrexia, hypotension, and death have been reported coincident with the co-administration of monoamine oxidase (MAO) inhibitors and products containing dextromethorphan.
Thus, concomitant administration of Promethazine Hydrochloride and Dextromethorphan Hydrobromide Oral Solution and MAO inhibitors should be avoided (see CONTRAINDICATIONS ).
Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAO inhibitors and phenothiazines are used concomitantly.
From the Methylene blue (PROVAYBLUE) label · effective 2025-05-28
Opioids and dextromethorphan may increase the risk of developing serotonin syndrome.
…including antidepressants like SSRIs (selective serotonin reuptake inhibitors), SNRIs (serotonin and norepinephrine reuptake inhibitors), MAOIs (monoamine oxidase inhibitors), bupropion, buspirone, clomipramine, mirtazapine, linezolid, opioids, and dextromethorphan because of the potential for serious CNS reactions, including potentially fatal serotonin syndrome.
Clinically significant drug interactions with PROVAYBLUE are described below: The concomitant use of PROVAYBLUE with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.