What the FDA labels say about taking them together
Lithium and mirtazapine
Mirtazapine's FDA label of August 6, 2025 names lithium in its drug interactions section; the lithium labels PlainMeds reads (4) do not name mirtazapine. The mirtazapine 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 lithium FDA label on DailyMed (effective December 23, 2025, Glenmark Pharmaceuticals Inc., USA); the mirtazapine FDA label on DailyMed (effective August 6, 2025, Organon LLC).
What does the lithium label say about mirtazapine?
Lithium's label (effective December 23, 2025) and its 3 other brand-application labels do not name mirtazapine in these sections. A label lists what its studies and reports found; it is not a complete list.
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
What does the mirtazapine label say about lithium?
Mirtazapine label, drug interactionsExamples SSRIs, SNRIs, triptans, tricyclic antidepressants, fentanyl, lithium, amphetamines, St. John's Wort, tramadol, tryptophan, buspirone Strong CYP3A Inducers Clinical Impact The concomitant use of strong CYP3A inducers with REMERON/REMERONSolTab decreases the plasma concentration of mirtazapine [see Clinical Pharmacology (12.3) ]. Intervention Increase the dose of REMERON/REMERONSolTab if needed with concomitant CYP3A inducer use. Conversely, a decrease in dosage of REMERON/REMERONSolTab may be needed if the CYP3A inducer is discontinued [see Dosage and Administration (2.5) ].
Mirtazapine label, warnings and precautionsThe risk is increased 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, i.e., MAOIs [see Contraindications (4), Drug Interactions (7) ].
Source: FDA drug label (REMERON), Organon LLC, effective August 6, 2025 (SPL set 98ad1917-a094-44f5-a28f-a64a8cfcd887), 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
| Lithium | Mirtazapine | |
|---|---|---|
| Labeled for | Bipolar disorder | Depression |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.104 per capsule 300 mg capsule | $0.063 per tablet 15 mg tablet |
| 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