What the FDA labels say about taking them together
Cimetidine and diazepam
Cimetidine's FDA label of July 15, 2026 names diazepam in its drug interactions section, and diazepam's label names cimetidine too. The diazepam label: “Inhibitors of CYP2C19 and CYP3A4 Inhibitors of CYP2C19 and CYP3A4 could decrease the rate of diazepam elimination; therefore, adverse reactions to VALTOCO may be increased.”
Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the diazepam FDA label on DailyMed (effective August 11, 2026, Waylis Therapuetics LLC).
What does the cimetidine label say about diazepam?
Cimetidine label, drug interactionsDrug Interactions Cimetidine tablets, apparently through an effect on certain microsomal enzyme systems, has been reported to reduce the hepatic metabolism of warfarin-type anticoagulants, phenytoin, propranolol, nifedipine, chlordiazepoxide, diazepam, certain tricyclic antidepressants, lidocaine, theophylline, and metronidazole, thereby delaying elimination and increasing blood levels of these drugs.
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 diazepam label say about cimetidine?
Diazepam label, drug interactionsAt present, this reaction is known to occur with cimetidine, ketoconazole, fluvoxamine, fluoxetine, and omeprazole.
Valtoco label (Neurelis, Inc, June 3, 2026), drug interactionsInhibitors of CYP2C19 and CYP3A4 Inhibitors of CYP2C19 (e.g., cimetidine, quinidine, and tranylcypromine) and CYP3A4 (e.g., ketoconazole, troleandomycin, and clotrimazole) could decrease the rate of diazepam elimination; therefore, adverse reactions to VALTOCO may be increased.
Diazepam label (Meridian Medical Technologies LLC, December 18, 2023), drug interactionsConcomitant Use with Cimetidine The clearance of diazepam and certain other benzodiazepines can be delayed in association with Tagamet (cimetidine) administration.
Source: FDA drug label (Valtoco, NDA211635), Neurelis, Inc, effective June 3, 2026 (SPL set 1a8bcc90-68fa-474d-832c-0df01e825f39), via openFDA
Source: FDA drug label (Diazepam, NDA020124), Meridian Medical Technologies LLC, effective December 18, 2023 (SPL set fa352464-14c8-49e9-b8b7-5a968b1cfa93), via openFDA
Source: FDA drug label (Valium), Waylis Therapuetics LLC, effective August 11, 2026 (SPL set 260e2041-2bb3-482f-850e-b5d47a7bdbe6), 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 | Diazepam | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Anxiety, Muscle spasms and spasticity |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 mg tablet | $0.0283 per tablet 10 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