Drug interactions
Dihydroergotamine + Phenytoin
Severity: Moderate
Dihydroergotamine and Phenytoin: 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
Phenytoin induces CYP3A4 and may lower dihydroergotamine exposure, reducing its antimigraine effect. Phenytoin-related changes are unpredictable and efficacy may be lost. The labeled concern for dihydroergotamine is with CYP3A4 inhibitors, not inducers, so the contraindication here is not supported by a safety rationale.
What this interaction means in plain words
Dihydroergotamine and Phenytoin 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.
Dihydroergotamine belongs to Central Nervous System; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing the metabolism of dihydroergotamine.
What to do
Monitor for reduced migraine response and consider an alternative acute therapy if dihydroergotamine becomes ineffective. Avoid adding CYP3A4 inhibitors if phenytoin is later stopped, as exposure may rise.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Other interactions of Dihydroergotamine
- Almotriptan + Dihydroergotamine Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
- Dihydroergotamine + Dopamine Contraindicated
- Dihydroergotamine + Dronedarone Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Dihydroergotamine + Eletriptan Contraindicated
Frequently asked questions
Can I take Dihydroergotamine with Phenytoin?
MediHelp rates the interaction as moderate. Dihydroergotamine and Phenytoin 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. Phenytoin induces CYP3A4 and may lower dihydroergotamine exposure, reducing its antimigraine effect. Phenytoin-related changes are unpredictable and efficacy may be lost. The labeled concern for dihydroergotamine is with CYP3A4 inhibitors, not inducers, so the contraindication here is not supported by a safety rationale.
How serious is the interaction between Dihydroergotamine and Phenytoin?
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 reduced migraine response and consider an alternative acute therapy if dihydroergotamine becomes ineffective. Avoid adding CYP3A4 inhibitors if phenytoin is later stopped, as exposure may rise.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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