What the FDA labels say about taking them together
Cimetidine and metformin
Metformin's FDA label of September 3, 2026 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name metformin. The metformin label: “Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin could increase systemic exposure to metformin and may increase the risk for lactic …”
Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the metformin FDA label on DailyMed (effective September 3, 2026, Granules India Ltd).
What does the cimetidine label say about metformin?
Cimetidine's label (effective July 15, 2026) does not name metformin 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 metformin label say about cimetidine?
Metformin label, drug interactionsDrugs that Reduce Metformin Hydrochloride Extended-Release Tablets Clearance Clinical Impact: Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (…) could increase systemic exposure to metformin and may increase the risk for lactic acidosis. Intervention: Consider the benefits and risks of concomitant use with metformin hydrochloride extended-release tablets. Examples: Ranolazine, vandetanib, dolutegravir, and cimetidine.
Riomet label (Sun Pharmaceutical Industries, Inc., December 6, 2018), drug interactions1. Examples:; 1. Ranolazine, vandetanib, dolutegravir, and cimetidine.
Source: FDA drug label (Riomet, NDA021591), Sun Pharmaceutical Industries, Inc., effective December 6, 2018 (SPL set 05d4df4b-dfe8-4828-b423-a3d4f2c4114a), via openFDA
Source: FDA drug label (METFORMIN HYDROCHLORIDE), Granules India Ltd, effective September 3, 2026 (SPL set 73197cb5-3e23-4ac0-b189-f9bc848bce66), 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 | Metformin | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Type 2 diabetes |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 mg tablet | $0.0145 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