Drug interactions
Duloxetine + Phentermine
Severity: Moderate
Duloxetine and Phentermine: 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
Phentermine is a sympathomimetic with some monoamine-releasing activity, and combined with duloxetine it may raise the risk of serotonin syndrome and increase blood pressure and heart rate. Reports are limited and the risk is largely theoretical.
What this interaction means in plain words
Duloxetine and Phentermine 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.
Duloxetine belongs to Central Nervous System; Phentermine belongs to Central Nervous System.
Why it happens
Additive monoaminergic effects from norepinephrine-releasing phentermine and duloxetine reuptake inhibition.
What to do
Monitor blood pressure, heart rate and signs of serotonin toxicity, particularly after dose increases. Consider alternatives in patients with uncontrolled hypertension or cardiovascular disease.
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 Duloxetine
- Duloxetine + Isocarboxazid Contraindicated
- Duloxetine + Linezolid Contraindicated
- Duloxetine + Methylene blue Contraindicated
- Duloxetine + Phenelzine Contraindicated
- Duloxetine + Procarbazine Contraindicated
- Duloxetine + Rasagiline Contraindicated
Other interactions of Phentermine
- Isocarboxazid + Phentermine Contraindicated
- Linezolid + Phentermine Contraindicated
- Phenelzine + Phentermine Contraindicated
- Phentermine + Procarbazine Contraindicated
- Phentermine + Rasagiline Contraindicated
- Phentermine + Selegiline Contraindicated
Frequently asked questions
Can I take Duloxetine with Phentermine?
MediHelp rates the interaction as moderate. Duloxetine and Phentermine 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. Phentermine is a sympathomimetic with some monoamine-releasing activity, and combined with duloxetine it may raise the risk of serotonin syndrome and increase blood pressure and heart rate. Reports are limited and the risk is largely theoretical.
How serious is the interaction between Duloxetine and Phentermine?
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 pressure, heart rate and signs of serotonin toxicity, particularly after dose increases. Consider alternatives in patients with uncontrolled hypertension or cardiovascular disease.
What other medicines interact with Duloxetine?
MediHelp also lists interactions of Duloxetine with, for example, Isocarboxazid, Linezolid, Methylene blue. The full list is on the Duloxetine page.
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