What the FDA labels say about taking them together
Diflunisal and lithium
Diflunisal's FDA label of August 4, 2026 names lithium in its drug interactions section; lithium's label does not name diflunisal itself but warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)). The diflunisal label: “Lithium NSAIDs have produced an elevation of plasma lithium levels and a reduction in renal lithium clearance.”
Check it at the source: the diflunisal FDA label on DailyMed (effective August 4, 2026, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.); the lithium FDA label on DailyMed (effective December 23, 2025, Glenmark Pharmaceuticals Inc., USA).
What does the diflunisal label say about lithium?
Diflunisal label, drug interactionsLithium NSAIDs have produced an elevation of plasma lithium levels and a reduction in renal lithium clearance.
Source: FDA drug label (diflunisal), Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective August 4, 2026 (SPL set 666f89b4-fd81-420a-a390-eb1cd4014f61), via openFDA; the full label on DailyMed
What does the lithium label say about diflunisal?
Lithium's label does not name diflunisal 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
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
| Diflunisal | Lithium | |
|---|---|---|
| Labeled for | Pain, Osteoarthritis, Rheumatoid arthritis | Bipolar disorder |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $1.06 per tablet 500 mg tablet | $0.104 per capsule 300 mg capsule |
| 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