What the FDA labels say about taking them together
Desvenlafaxine and methylene blue
Desvenlafaxine's FDA label of January 27, 2023 names methylene blue in its contraindications section; methylene blue's label does not name desvenlafaxine itself but warns about its class (SNRIs (serotonin and norepinephrine reuptake inhibitors)). The desvenlafaxine label: “… disorders. • In a patient who is being treated with linezolid or intravenous methylene blue. [see, and ].”
Check it at the source: the desvenlafaxine FDA label on DailyMed (effective January 27, 2023, Alembic Pharmaceuticals Limited); the methylene blue FDA label on DailyMed (effective May 28, 2025, American Regent, Inc.).
What does the desvenlafaxine label say about methylene blue?
Desvenlafaxine label, contraindicationsStarting desvenlafaxine in a patient who is being treated with MAOIs such as linezolid or intravenous methylene blue is also contraindicated because of an increased risk of serotonin syndrome [see Dosage and Administration (2.6) and Warnings and Precautions (5.2)].
Desvenlafaxine label, drug interactionsIn addition, do not start desvenlafaxine in a patient who is being treated with linezolid or intravenous methylene blue [see Dosage and Administration (2.6 ), Contraindications (4) and Warnings and Precautions (5.2)].
Desvenlafaxine label, warnings and precautionsThe development of a potentially life-threatening serotonin syndrome has been reported with SNRIs and SSRIs, including desvenlafaxine, alone but particularly with concomitant use of other serotonergic drugs (including triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. John's Wort), and with drugs that impair metabolism of serotonin (in particular, MAOIs, both those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue).
Pristiq Extended-Release label (Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., April 28, 2026), drug interactionsIntervention; Concomitant use of PRISTIQ is contraindicated: • With an MAOI intended to treat psychiatric disorders or within 7 days of stopping treatment with PRISTIQ. • Within 14 days of stopping an MAOI intended to treat psychiatric disorders. • In a patient who is being treated with linezolid or intravenous methylene blue. [see, and ].
Pristiq Extended-Release label (Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., April 28, 2026), warnings and precautionsIf it is necessary to initiate treatment with an MAOI such as linezolid or intravenous methylene blue in a patient taking PRISTIQ, discontinue PRISTIQ before initiating treatment with the MAOI [see Contraindications (4), Drug Interactions (7.1) ].
Source: FDA drug label (Pristiq Extended-Release, NDA021992), Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective April 28, 2026 (SPL set 0f43610c-f290-46ea-d186-4f998ed99fce), via openFDA
Source: FDA drug label (Desvenlafaxine), Alembic Pharmaceuticals Limited, effective January 27, 2023 (SPL set 9f74708c-6f6a-46cf-8c79-87a25c2bb6f8), via openFDA; the full label on DailyMed
What does the methylene blue label say about desvenlafaxine?
Methylene blue's label does not name desvenlafaxine itself; it warns about its class (SNRIs (serotonin and norepinephrine reuptake inhibitors)):
Methylene blue label, drug interactionsAvoid concomitant use of PROVAYBLUE with medicinal products that enhance serotonergic transmission 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.
Methylene blue label, boxed warningAvoid 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 )].
Source: FDA drug label (PROVAYBLUE), NDA204630 (Provepharm Sas), as published by American Regent, Inc., effective May 28, 2025 (SPL set 4f6848e5-35ed-4046-b13c-3032b5ba3232), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Desvenlafaxine | Methylene blue | |
|---|---|---|
| Labeled for | Depression | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.396 per unit 50 mg | n/a |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once