Drug interactions
Hydralazine + Phentermine
Severity: Moderate
Hydralazine 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 has sympathomimetic activity that can elevate blood pressure and heart rate. This can counteract the antihypertensive action of hydralazine and cause reduced blood pressure control. Additive tachycardia is also possible.
What this interaction means in plain words
Hydralazine 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.
Hydralazine belongs to Cardiovascular; Phentermine belongs to Central Nervous System.
Why it happens
Pharmacodynamic antagonism, as sympathomimetic release of catecholamines opposes the vasodilating effect of hydralazine.
What to do
Monitor blood pressure and heart rate at baseline and during therapy. Adjust the antihypertensive regimen or stop phentermine if hypertension persists.
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 Hydralazine
- Amifostine + Hydralazine Major
- Aceclofenac + Hydralazine Moderate
- Acemetacin + Hydralazine Moderate
- Aldesleukin + Hydralazine Moderate
- Avanafil + Hydralazine Moderate
- Benzphetamine + Hydralazine Moderate
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 Hydralazine with Phentermine?
MediHelp rates the interaction as moderate. Hydralazine 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 has sympathomimetic activity that can elevate blood pressure and heart rate. This can counteract the antihypertensive action of hydralazine and cause reduced blood pressure control. Additive tachycardia is also possible.
How serious is the interaction between Hydralazine 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 baseline and during therapy. Adjust the antihypertensive regimen or stop phentermine if hypertension persists.
What other medicines interact with Hydralazine?
MediHelp also lists interactions of Hydralazine with, for example, Amifostine, Aceclofenac, Acemetacin. The full list is on the Hydralazine page.
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