Methylene blue and Morphine interaction
Methylene blue and Morphine: 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 Methylene blue (PROVAYBLUE) label · effective 2025-05-28
WARNING: SEROTONIN SYNDROME WITH CONCOMITANT USE OF SEROTONERGIC DRUGS AND OPIOIDS PROVAYBLUE may cause serious or fatal serotonergic syndrome when used in combination with serotonergic drugs and opioids.
Avoid concomitant use of PROVAYBLUE with selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs) and opioids. [see Warnings and Precautions ( 5.1 ) and Drug Interactions ( 7.1 )].
WARNING: SEROTONIN SYNDROME WITH CONCOMITANT USE OF SEROTONERGIC DRUGS AND OPIOIDS See full prescribing information for complete boxed warning.
PROVAYBLUE may cause serious or fatal serotonergic syndrome when used in combination with serotonergic drugs and opioids.
Serotonin Syndrome with Concomitant Use of Serotonergic Drugs and Opioids The development of serotonin syndrome has been reported with the use of methylene blue class products.
From the Morphine (Morphine Sulfate) label · effective 2026-02-03
• Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days [see Warnings and Precautions ( 5.9 ) and Drug Interactions ( 7 )].
• Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days.
Interaction with Monoamine Oxidase Inhibitors Monoamine oxidase inhibitors (MAOIs) may potentiate the effects of morphine, including respiratory depression, coma, and confusion.
Morphine Sulfate Oral Solution should not be used in patients taking MAOIs or within 14 days of stopping such treatment.
Monoamine Oxidase Inhibitors (MAOIs) Clinical Impact: MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity (e.g., respiratory depression, coma) [see Warnings and Precautions ( 5.3 , 5.9 )].
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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.