What the FDA labels say about taking them together
Fentanyl and lithium
Lithium's FDA label of December 23, 2025 names fentanyl in its warnings and precautions section; the fentanyl labels PlainMeds reads (2) do not name lithium. The lithium 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 fentanyl FDA label on DailyMed (effective March 6, 2026, Hikma Pharmaceuticals USA Inc.); the lithium FDA label on DailyMed (effective December 23, 2025, Glenmark Pharmaceuticals Inc., USA).
What does the fentanyl label say about lithium?
Fentanyl's label (effective March 6, 2026) and its 1 other brand-application label do not name lithium in these sections. A label lists what its studies and reports found; it is not a complete list.
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
What does the lithium label say about fentanyl?
Lithium label, warnings and precautionsThe risk is increased with concomitant use of other serotonergic drugs (including selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors, triptans, tricyclic antidepressants, fentanyl, tramadol, tryptophan, buspirone, and St. John’s Wort) and with drugs that impair metabolism of serotonin, i.e., MAOIs [see Drug Interactions ( 7.1 )].
Source: FDA drug label (Lithium Carbonate), Glenmark Pharmaceuticals Inc., USA, effective December 23, 2025 (SPL set 63b3790f-a9b5-47f4-bae1-ddf8b43c13c1), 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
| Fentanyl | Lithium | |
|---|---|---|
| Labeled for | Pain | Bipolar disorder |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $1.79 per mL 100 mcg/2 mL vial | $0.104 per capsule 300 mg capsule |
| Shortage now | In shortage | 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