Duloxetine and Methylene blue interaction
Duloxetine and Methylene blue: 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 Duloxetine label · effective 2026-03-02
…Delayed-Release Capsules prior to initiation of an MAOI to treat psychiatric disorders. [see Dosage and Administration ( 2.7 ), Warnings and Precautions ( 5.4 )]. who are using other MAOIs such as linezolid or intravenous methylene blue because of an increased risk of serotonin syndrome [see Dosage and Administration ( 2.8 ), Warnings and Precautions ( 5.4 )].
Do not start Duloxetine Delayed-Release Capsules in a patient who is being treated with linezolid or intravenous methylene blue ( 4 )
Duloxetine Delayed-Release Capsules are contraindicated in patients who are using or within 14 days of stopping an MAOI intended to treat psychiatric disorders because of an increased risk of serotonin syndrome.
Concomitant use of monoamine oxidase inhibitors (MAOIs), or use within 14 days of stopping MAOIs ( 4 )
Serotonin Syndrome: Increased risk when co-administered with other serotonergic agents but also when taken alone.
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.
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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.