What the FDA labels say about taking them together
Desvenlafaxine and fentanyl
Desvenlafaxine's FDA label of January 27, 2023 names fentanyl in its warnings and precautions section; fentanyl's label does not name desvenlafaxine itself but warns about its class (SNRIs (serotonin and norepinephrine reuptake inhibitors)). The desvenlafaxine label: “The risk is increased with concomitant use of other serotonergic drugs and with drugs that impair metabolism of serotonin, i.e., MAOIs.”
Check it at the source: the desvenlafaxine FDA label on DailyMed (effective January 27, 2023, Alembic Pharmaceuticals Limited); the fentanyl FDA label on DailyMed (effective March 6, 2026, Hikma Pharmaceuticals USA Inc.).
What does the desvenlafaxine label say about fentanyl?
Desvenlafaxine label, warnings and precautionsSerotonin Syndrome: Serotonin syndrome has been reported with SSRIs and SNRIs, including with desvenlafaxine extended-release tablets, both when taken alone, but especially when co-administered with other serotonergic agents (including triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. John's Wort). If such symptoms occur, discontinue desvenlafaxine and initiate supportive treatment.
Pristiq Extended-Release label (Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., April 28, 2026), warnings and precautionsThe risk is increased with concomitant use of other serotonergic drugs (including triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, meperidine, methadone, tryptophan, buspirone, amphetamines, and St. John's Wort) and with drugs that impair metabolism of serotonin, i.e., MAOIs [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 fentanyl label say about desvenlafaxine?
Fentanyl's label does not name desvenlafaxine itself; it warns about its class (SNRIs (serotonin and norepinephrine reuptake inhibitors)):
Fentanyl label, warnings and precautionsIf a patient is suspected to be experiencing OIH, carefully consider appropriately decreasing the dose of the current opioid analgesic or opioid rotation (safely switching the patient to a different opioid moiety) [see Dosage and Administration (2), Warnings and Precautions (5.7) ] . 5.8 Serotonin Syndrome with Concomitant Use of Serotonergic Drugs Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of fentanyl with serotonergic drugs. …
Fentanyl label, warnings and precautionsSyndrome with Concomitant Use of Serotonergic Drugs Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of fentanyl with serotonergic drugs. Serotonergic drugs include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that affect the serotonergic neurotransmitter system (e.g., mirtazapine, trazadone, tramadol), certain …
Source: FDA drug label (Fentanyl Citrate), Hikma Pharmaceuticals USA Inc., effective March 6, 2026 (SPL set ce5db1c2-feb1-4ad2-847a-d02e865bd47e), 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 | Fentanyl | |
|---|---|---|
| Labeled for | Depression | Pain |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.396 per unit 50 mg | $1.79 per mL 100 mcg/2 mL vial |
| Shortage now | No current entry | In shortage |
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