Drug interactions
Dihydroergotamine intranasal + Phenytoin
Severity: Moderate
Dihydroergotamine intranasal 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 reduce systemic dihydroergotamine exposure from the nasal spray, lessening its antimigraine effect. The clinical impact is predicted rather than well documented. Ergot toxicity concerns relate to CYP3A4 inhibitors, not inducers.
What this interaction means in plain words
Dihydroergotamine intranasal 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.
Why it happens
Phenytoin induces CYP3A4, increasing the metabolism of dihydroergotamine.
What to do
Monitor for loss of migraine relief and switch to a different acute treatment if response is inadequate. Reassess dihydroergotamine exposure if phenytoin is stopped.
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
Frequently asked questions
Can I take Dihydroergotamine intranasal with Phenytoin?
MediHelp rates the interaction as moderate. Dihydroergotamine intranasal 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 reduce systemic dihydroergotamine exposure from the nasal spray, lessening its antimigraine effect. The clinical impact is predicted rather than well documented. Ergot toxicity concerns relate to CYP3A4 inhibitors, not inducers.
How serious is the interaction between Dihydroergotamine intranasal 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 loss of migraine relief and switch to a different acute treatment if response is inadequate. Reassess dihydroergotamine exposure if phenytoin is stopped.
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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