Drug interactions
Melatonin + Phenobarbital
Severity: Moderate
Melatonin and Phenobarbital: 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
Phenobarbital is a sedative anticonvulsant and melatonin may add to drowsiness. Phenobarbital also induces hepatic enzymes and may lower melatonin exposure, which could reduce its sleep-promoting effect.
What this interaction means in plain words
Melatonin and Phenobarbital 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.
Why it happens
Additive CNS depression plus phenobarbital induction of CYP1A2-mediated melatonin metabolism.
What to do
Monitor for sedation and for reduced melatonin efficacy. Adjust the melatonin dose according to response.
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 Melatonin
- Fluvoxamine + Melatonin Major
- Alfentanil + Melatonin Moderate
- Belladonna and opium + Melatonin Moderate
- Buprenorphine buccal + Melatonin Moderate
- Butabarbital + Melatonin Moderate
- Butalbital + Melatonin Moderate
Frequently asked questions
Can I take Melatonin with Phenobarbital?
MediHelp rates the interaction as moderate. Melatonin and Phenobarbital 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. Phenobarbital is a sedative anticonvulsant and melatonin may add to drowsiness. Phenobarbital also induces hepatic enzymes and may lower melatonin exposure, which could reduce its sleep-promoting effect.
How serious is the interaction between Melatonin and Phenobarbital?
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 sedation and for reduced melatonin efficacy. Adjust the melatonin dose according to response.
What other medicines interact with Melatonin?
MediHelp also lists interactions of Melatonin with, for example, Fluvoxamine, Alfentanil, Belladonna and opium. The full list is on the Melatonin page.
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