Drug interactions
Fluvoxamine + Phentermine
Severity: Moderate
Fluvoxamine 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 combining it with an SSRI has been associated with rare serotonin syndrome and increased blood pressure or heart rate. The evidence is limited, mostly from case reports.
What this interaction means in plain words
Fluvoxamine 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.
Fluvoxamine belongs to Central Nervous System; Phentermine belongs to Central Nervous System.
Why it happens
Additive monoaminergic effects from monoamine release plus serotonin reuptake inhibition.
What to do
Monitor blood pressure, heart rate and signs of serotonin toxicity; avoid in patients with prior serotonin syndrome.
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 Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue 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 Fluvoxamine with Phentermine?
MediHelp rates the interaction as moderate. Fluvoxamine 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 combining it with an SSRI has been associated with rare serotonin syndrome and increased blood pressure or heart rate. The evidence is limited, mostly from case reports.
How serious is the interaction between Fluvoxamine 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; avoid in patients with prior serotonin syndrome.
What other medicines interact with Fluvoxamine?
MediHelp also lists interactions of Fluvoxamine with, for example, Agomelatine, Alosetron, Fezolinetant. The full list is on the Fluvoxamine page.
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