Drug interactions
Clemastine + Fenfluramine
Severity: Moderate
Clemastine and Fenfluramine: 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
Fenfluramine can cause somnolence, and clemastine is sedating, so additive drowsiness is possible. The legacy suggestion of opposing effects is not well supported.
What this interaction means in plain words
Clemastine and Fenfluramine 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.
Clemastine belongs to Respiratory; Fenfluramine belongs to Central Nervous System.
Why it happens
Probable additive central nervous system depressant effects.
What to do
Monitor for excessive sedation and impaired alertness when starting clemastine in patients on fenfluramine. Counsel about driving.
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 Clemastine
Other interactions of Fenfluramine
- Fenfluramine + Isocarboxazid Contraindicated
- Fenfluramine + Linezolid Contraindicated
- Fenfluramine + Phenelzine Contraindicated
- Fenfluramine + Selegiline Contraindicated
- Fenfluramine + Tranylcypromine Contraindicated
- Almotriptan + Fenfluramine Major
Frequently asked questions
Can I take Clemastine with Fenfluramine?
MediHelp rates the interaction as moderate. Clemastine and Fenfluramine 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. Fenfluramine can cause somnolence, and clemastine is sedating, so additive drowsiness is possible. The legacy suggestion of opposing effects is not well supported.
How serious is the interaction between Clemastine and Fenfluramine?
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 excessive sedation and impaired alertness when starting clemastine in patients on fenfluramine. Counsel about driving.
What other medicines interact with Clemastine?
MediHelp also lists interactions of Clemastine with, for example, Alfentanil, Benzhydrocodone / acetaminophen, Buprenorphine buccal. The full list is on the Clemastine page.
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