Drug interactions
Finasteride + Isoniazid
Severity: Minor
Finasteride and Isoniazid: 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
Isoniazid is a weak, variable CYP3A4 inhibitor and could modestly raise finasteride levels in theory. No meaningful clinical consequence is established.
What this interaction means in plain words
Finasteride and Isoniazid have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Finasteride belongs to Genitourinary; Isoniazid belongs to Anti Bacterial.
Why it happens
Possible weak inhibition of CYP3A4 by isoniazid reducing finasteride metabolism.
What to do
No action is generally required. Monitor for finasteride adverse effects only if clinically suggested.
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 Finasteride
- Finasteride + Levoketoconazole Moderate
- Finasteride + Nefazodone Moderate
- Finasteride + Rifampin Moderate
- Finasteride + St john's wort Moderate
- Amobarbital + Finasteride Minor
- Aprepitant + Finasteride Minor
Other interactions of Isoniazid
Frequently asked questions
Can I take Finasteride with Isoniazid?
MediHelp rates the interaction as minor. Finasteride and Isoniazid have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Isoniazid is a weak, variable CYP3A4 inhibitor and could modestly raise finasteride levels in theory. No meaningful clinical consequence is established.
How serious is the interaction between Finasteride and Isoniazid?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No action is generally required. Monitor for finasteride adverse effects only if clinically suggested.
What other medicines interact with Finasteride?
MediHelp also lists interactions of Finasteride with, for example, Levoketoconazole, Nefazodone, Rifampin. The full list is on the Finasteride page.
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