Drug interactions
Ketotifen + Primidone
Severity: Moderate
Ketotifen and Primidone: 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
Primidone is metabolized partly to phenobarbital and causes sedation, and ketotifen is a sedating antihistamine. Combined use can increase drowsiness, dizziness and impaired coordination, especially when primidone is started or the dose increased.
What this interaction means in plain words
Ketotifen and Primidone 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 belongs to Respiratory; Primidone belongs to Central Nervous System.
Why it happens
Additive central nervous system depression from antihistamine and barbiturate-type anticonvulsant activity.
What to do
Counsel on sedation and avoid driving until the response is known. Consider a non-sedating antihistamine if sedation is troublesome.
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 + Phenobarbital Moderate
- Ketotifen + Pholcodine Moderate
- Ketotifen + Protriptyline Moderate
- Ketotifen + Quazepam Moderate
- Ketotifen + Rotigotine Moderate
- Ketotifen + Sufentanil Moderate
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Ketotifen with Primidone?
MediHelp rates the interaction as moderate. Ketotifen and Primidone 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. Primidone is metabolized partly to phenobarbital and causes sedation, and ketotifen is a sedating antihistamine. Combined use can increase drowsiness, dizziness and impaired coordination, especially when primidone is started or the dose increased.
How serious is the interaction between Ketotifen and Primidone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Counsel on sedation and avoid driving until the response is known. Consider a non-sedating antihistamine if sedation is troublesome.
What other medicines interact with Ketotifen?
MediHelp also lists interactions of Ketotifen with, for example, Phenobarbital, Pholcodine, Protriptyline. The full list is on the Ketotifen page.
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