What the FDA labels say about taking them together
Cimetidine and leflunomide
Leflunomide's FDA label of June 4, 2025 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name leflunomide. The leflunomide label: “In patients taking ARAVA, exposure of drugs which are OAT3 substrates may be increased.”
Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the leflunomide FDA label on DailyMed (effective June 4, 2025, sanofi-aventis U.S. LLC).
What does the cimetidine label say about leflunomide?
Cimetidine's label (effective July 15, 2026) does not name leflunomide in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cimetidine), Mylan Pharmaceuticals Inc., effective July 15, 2026 (SPL set 06c0a509-026f-44e0-9975-a94a8de51d43), via openFDA; the full label on DailyMed
What does the leflunomide label say about cimetidine?
Leflunomide label, drug interactionsIn patients taking ARAVA, exposure of drugs which are OAT3 substrates (e.g., cefaclor, cimetidine, ciprofloxacin, penicillin G, ketoprofen, furosemide, methotrexate, zidovudine) may be increased.
Source: FDA drug label (Arava), sanofi-aventis U.S. LLC, effective June 4, 2025 (SPL set 320f63f2-fac3-4aee-aff8-85724e00ef52), 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
| Cimetidine | Leflunomide | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Rheumatoid arthritis |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 mg tablet | $0.324 per tablet 10 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
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