What the FDA labels say about taking them together
Cimetidine and terbinafine
Terbinafine's FDA label of October 17, 2025 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name terbinafine. The terbinafine label: “Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor.”
Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the terbinafine FDA label on DailyMed (effective October 17, 2025, PD-Rx Pharmaceuticals, Inc.).
What does the cimetidine label say about terbinafine?
Cimetidine's label (effective July 15, 2026) does not name terbinafine 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 terbinafine label say about cimetidine?
Terbinafine label, drug interactionsTerbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor.
Source: FDA drug label (Terbinafine Hydrochloride), PD-Rx Pharmaceuticals, Inc., effective October 17, 2025 (SPL set 2df111dc-ecac-4161-9e22-38436eb37c1f), 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 | Terbinafine | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Fungal infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 mg tablet | $0.143 per tablet 250 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