Drug interactions
Amitriptyline + Phentermine
Severity: Moderate
Amitriptyline 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 releases norepinephrine, and tricyclics can both blunt its indirect action and increase cardiovascular stimulation. The combination may cause hypertension, tachycardia and, rarely, serotonergic toxicity.
What this interaction means in plain words
Amitriptyline 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.
Amitriptyline belongs to Central Nervous System; Phentermine belongs to Central Nervous System.
Why it happens
Tricyclics block neuronal uptake of indirect sympathomimetics and norepinephrine reuptake, altering adrenergic response.
What to do
Monitor blood pressure and heart rate at the start of combined therapy and after dose changes. Stop phentermine if significant hypertension or palpitations develop.
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 Amitriptyline
- Amitriptyline + Isocarboxazid Contraindicated
- Amitriptyline + Methylene blue Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amitriptyline + Procarbazine Contraindicated
- Amitriptyline + Safinamide 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 Amitriptyline with Phentermine?
MediHelp rates the interaction as moderate. Amitriptyline 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 releases norepinephrine, and tricyclics can both blunt its indirect action and increase cardiovascular stimulation. The combination may cause hypertension, tachycardia and, rarely, serotonergic toxicity.
How serious is the interaction between Amitriptyline 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 and heart rate at the start of combined therapy and after dose changes. Stop phentermine if significant hypertension or palpitations develop.
What other medicines interact with Amitriptyline?
MediHelp also lists interactions of Amitriptyline with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Amitriptyline page.
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