What the FDA labels say about taking them together
Lithium and naproxen
Naproxen's FDA label of March 12, 2026 names lithium in its drug interactions (prescription label) section; lithium's label does not name naproxen itself but warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)). The naproxen label: “NSAIDs have produced elevations in plasma lithium levels and reductions in renal lithium clearance. The mean minimum lithium concentration increased 15%, and the renal clearance decreased by approximately 20%. …”
Check it at the source: the lithium FDA label on DailyMed (effective December 23, 2025, Glenmark Pharmaceuticals Inc., USA); the naproxen FDA label on DailyMed (effective March 12, 2026, Bayer HealthCare LLC.).
What does the lithium label say about naproxen?
Lithium's label does not name naproxen itself; it warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)):
Lithium label, drug interactionsDiuretics, NSAID, renin-angiotensin system antagonists, or metronidazole may increase lithium serum concentrations.
Lithium label, drug interactionsReduce lithium dosage based on serum lithium concentration and clinical response [see Dosage and Administration ( 2.3 ), Warning and Precautions ( 5.3 )]. Non-Steroidal Anti-inflammatory Drugs (NSAID)
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 naproxen label say about lithium?
Naproxen label, drug interactions (prescription label)Clinical Impact: NSAIDs have produced elevations in plasma lithium levels and reductions in renal lithium clearance. The mean minimum lithium concentration increased 15%, and the renal clearance decreased by approximately 20%. This effect has been attributed to NSAID inhibition of renal prostaglandin synthesis. Intervention: During concomitant use of naproxen tablets or naproxen sodium tablets and lithium, monitor patients for signs of lithium toxicity.
Source: FDA drug label (Aleve Caplets), Bayer HealthCare LLC., effective March 12, 2026 (SPL set 02941928-128a-2c88-e063-6294a90ac6ba), 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 | Naproxen | |
|---|---|---|
| Labeled for | Bipolar disorder | Fever, Rheumatoid arthritis, Osteoarthritis, Gout, Pain, Cough and cold |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.104 per capsule 300 mg capsule | $0.0565 per tablet 500 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