Drug interactions
Dutasteride + Phenytoin
Severity: Minor
Dutasteride and Phenytoin: minor 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 is a potent CYP3A4 inducer and can lower dutasteride concentrations, possibly reducing its effect on prostate volume and symptoms. The clinical importance has not been well studied.
What this interaction means in plain words
Dutasteride and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Dutasteride belongs to Genitourinary; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, accelerating dutasteride metabolism.
What to do
Monitor urinary symptoms and PSA response; consider an alternative if efficacy is clearly diminished.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Dutasteride
- Dutasteride + Levoketoconazole Moderate
- Dutasteride + Nefazodone Moderate
- Dutasteride + Rifampin Moderate
- Dutasteride + St john's wort Moderate
- Amobarbital + Dutasteride Minor
- Aprepitant + Dutasteride Minor
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 Dutasteride with Phenytoin?
MediHelp rates the interaction as minor. Dutasteride and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenytoin is a potent CYP3A4 inducer and can lower dutasteride concentrations, possibly reducing its effect on prostate volume and symptoms. The clinical importance has not been well studied.
How serious is the interaction between Dutasteride and Phenytoin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor urinary symptoms and PSA response; consider an alternative if efficacy is clearly diminished.
What other medicines interact with Dutasteride?
MediHelp also lists interactions of Dutasteride with, for example, Levoketoconazole, Nefazodone, Rifampin. The full list is on the Dutasteride page.
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