Drug interactions
Phentermine + Trazodone
Severity: Moderate
Phentermine and Trazodone: 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 combining it with serotonergic trazodone has been linked to a risk of serotonin syndrome. Additive effects on blood pressure and heart rate are also possible.
What this interaction means in plain words
Phentermine and Trazodone 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 belongs to Central Nervous System; Trazodone belongs to Central Nervous System.
Why it happens
Additive serotonergic and noradrenergic effects from monoamine release by phentermine and serotonergic activity of trazodone.
What to do
Monitor for serotonin toxicity and for changes in blood pressure and heart rate, particularly after dose increases. Stop phentermine if signs of serotonin syndrome appear.
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 Trazodone
- Arsenic trioxide + Trazodone Contraindicated
- Ibutilide + Trazodone Contraindicated
- Isocarboxazid + Trazodone Contraindicated
- Levoketoconazole + Trazodone Contraindicated
- Methylene blue + Trazodone Contraindicated
- Phenelzine + Trazodone 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 Phentermine with Trazodone?
MediHelp rates the interaction as moderate. Phentermine and Trazodone 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 combining it with serotonergic trazodone has been linked to a risk of serotonin syndrome. Additive effects on blood pressure and heart rate are also possible.
How serious is the interaction between Phentermine and Trazodone?
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 for serotonin toxicity and for changes in blood pressure and heart rate, particularly after dose increases. Stop phentermine if signs of serotonin syndrome appear.
What other medicines interact with Trazodone?
MediHelp also lists interactions of Trazodone with, for example, Arsenic trioxide, Ibutilide, Isocarboxazid. The full list is on the Trazodone page.
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