Drug interactions
Dextroamphetamine + Phentermine
Severity: Major
Dextroamphetamine and Phentermine: major interaction.
Last updated Sources: Health Canada product monograph
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
Both are sympathomimetic stimulants, so combined use can cause marked hypertension, tachycardia, palpitations, insomnia and anxiety. Using two such agents has no established benefit and raises cardiovascular risk.
What this interaction means in plain words
Dextroamphetamine and Phentermine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Dextroamphetamine belongs to Central Nervous System; Phentermine belongs to Central Nervous System.
Why it happens
Additive sympathomimetic effects from catecholamine release.
What to do
Avoid using both together. If unavoidable, monitor blood pressure, heart rate and psychiatric symptoms.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Dextroamphetamine
- Dextroamphetamine + Isocarboxazid Contraindicated
- Dextroamphetamine + Linezolid Contraindicated
- Dextroamphetamine + Methylene blue Contraindicated
- Dextroamphetamine + Phenelzine Contraindicated
- Dextroamphetamine + Rasagiline Contraindicated
- Dextroamphetamine + 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 Dextroamphetamine with Phentermine?
MediHelp rates the interaction as major. Dextroamphetamine and Phentermine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both are sympathomimetic stimulants, so combined use can cause marked hypertension, tachycardia, palpitations, insomnia and anxiety. Using two such agents has no established benefit and raises cardiovascular risk.
How serious is the interaction between Dextroamphetamine and Phentermine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid using both together. If unavoidable, monitor blood pressure, heart rate and psychiatric symptoms.
What other medicines interact with Dextroamphetamine?
MediHelp also lists interactions of Dextroamphetamine with, for example, Isocarboxazid, Linezolid, Methylene blue. The full list is on the Dextroamphetamine page.
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