Drug interactions
Fluoxetine + Tolbutamide
Severity: Moderate
Fluoxetine 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
Tolbutamide is cleared mainly by CYP2C9, which fluoxetine inhibits, so tolbutamide levels may increase. Fluoxetine may also lower glucose independently, increasing the risk of hypoglycemia.
What this interaction means in plain words
Fluoxetine 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.
Fluoxetine belongs to Central Nervous System; Tolbutamide belongs to Endocrine.
Why it happens
Inhibition of CYP2C9-mediated tolbutamide metabolism combined with additive glucose lowering.
What to do
Monitor blood glucose closely when fluoxetine is started, changed or stopped, and lower the tolbutamide dose if hypoglycemia occurs.
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?
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Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
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 Fluoxetine with Tolbutamide?
MediHelp rates the interaction as moderate. Fluoxetine 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. Tolbutamide is cleared mainly by CYP2C9, which fluoxetine inhibits, so tolbutamide levels may increase. Fluoxetine may also lower glucose independently, increasing the risk of hypoglycemia.
How serious is the interaction between Fluoxetine 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 closely when fluoxetine is started, changed or stopped, and lower the tolbutamide dose if hypoglycemia occurs.
What other medicines interact with Fluoxetine?
MediHelp also lists interactions of Fluoxetine with, for example, Isocarboxazid, Mavacamten, Methylene blue. The full list is on the Fluoxetine page.
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