Drug interactions
Ketotifen + Phenobarbital
Severity: Moderate
Ketotifen 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
Ketotifen has sedating antihistamine properties, and phenobarbital is a barbiturate that depresses the central nervous system. Combined use may produce additive drowsiness and impaired psychomotor performance. The risk is greater with oral ketotifen than with the ophthalmic form, which has low systemic exposure.
What this interaction means in plain words
Ketotifen 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 central nervous system depression from H1-antihistamine activity and barbiturate GABA-A potentiation.
What to do
Warn the patient about drowsiness and advise against driving or operating machinery until the response is known. Consider a non-sedating antihistamine if sedation becomes problematic.
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 Ketotifen
- Ketotifen + Pholcodine Moderate
- Ketotifen + Primidone Moderate
- Ketotifen + Protriptyline Moderate
- Ketotifen + Quazepam Moderate
- Ketotifen + Rotigotine Moderate
- Ketotifen + Sufentanil Moderate
Frequently asked questions
Can I take Ketotifen with Phenobarbital?
MediHelp rates the interaction as moderate. Ketotifen 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. Ketotifen has sedating antihistamine properties, and phenobarbital is a barbiturate that depresses the central nervous system. Combined use may produce additive drowsiness and impaired psychomotor performance. The risk is greater with oral ketotifen than with the ophthalmic form, which has low systemic exposure.
How serious is the interaction between Ketotifen 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: Warn the patient about drowsiness and advise against driving or operating machinery until the response is known. Consider a non-sedating antihistamine if sedation becomes problematic.
What other medicines interact with Ketotifen?
MediHelp also lists interactions of Ketotifen with, for example, Pholcodine, Primidone, Protriptyline. The full list is on the Ketotifen page.
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