Drug interactions
Cimetidine + Tolbutamide
Severity: Moderate
Cimetidine and Tolbutamide: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Cimetidine can modestly increase tolbutamide levels and its glucose-lowering effect, with a risk of hypoglycemia. The legacy rationale of gastric pH is not the main mechanism.
What this interaction means in plain words
Cimetidine and Tolbutamide can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Cimetidine belongs to Gastrointestinal Tract; Tolbutamide belongs to Endocrine.
Why it happens
Cimetidine inhibits CYP2C9 and other hepatic enzymes that metabolize tolbutamide, reducing its clearance.
What to do
Monitor blood glucose when starting or stopping cimetidine and reduce the tolbutamide dose if hypoglycemia occurs. Famotidine is an alternative.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Cimetidine and Tolbutamide, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
Other interactions of Tolbutamide
- Glyburide-metformin + Tolbutamide Major
- Insulin degludec-liraglutide + Tolbutamide Major
- Aceclofenac + Tolbutamide Moderate
- Acemetacin + Tolbutamide Moderate
- Acetylsalicylic acid + Tolbutamide Moderate
- Albiglutide + Tolbutamide Moderate
Frequently asked questions
Can I take Cimetidine with Tolbutamide?
MediHelp rates the interaction as moderate. Cimetidine and Tolbutamide can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Cimetidine can modestly increase tolbutamide levels and its glucose-lowering effect, with a risk of hypoglycemia. The legacy rationale of gastric pH is not the main mechanism.
How serious is the interaction between Cimetidine and Tolbutamide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood glucose when starting or stopping cimetidine and reduce the tolbutamide dose if hypoglycemia occurs. Famotidine is an alternative.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
