Does Finasteride Interact With Testosterone?
Because of the ability of Type II 5α-reductase inhibitors to inhibit the conversion of testosterone to 5α-dihydrotestosterone (DHT), finasteride may cause abnormalities of the external genitalia of a male fetus of a pregnant woman who receives finasteride.
Severity: Contraindicated
Severity basis: contraindications section (keywords: contraindications section). Combining Finasteride (5-alpha reductase inhibitor) and Testosterone (Androgen (testosterone replacement)) is classified as a contraindicated interaction.
What to Do
This combination is contraindicated on the FDA label. Do not take these together unless your prescriber explicitly directs it.
How This Interaction Works
Interactions like this one can happen when two medicines have overlapping effects, or when one changes how the other is absorbed, broken down, or cleared from the body. Finasteride is a 5-alpha reductase inhibitor and Testosterone is a androgen (testosterone replacement); together they are documented as a contraindicated interaction. How much this matters depends on your dose, your other medications, and your overall health.
If You Take Both Medications
If you have been prescribed both Finasteride and Testosterone, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.
From the FDA Label
Because of the ability of Type II 5α-reductase inhibitors to inhibit the conversion of testosterone to 5α-dihydrotestosterone (DHT), finasteride may cause abnormalities of the external genitalia of a male fetus of a pregnant woman who receives finasteride.
Source: FDA structured product labeling (set_id 00e934bb-c15b-490a-a852-839689a1231a).
Testosterone
Androgen (testosterone replacement)
Brands: Depo-Testosterone, Xyosted
View Testosterone safety profileCheck these against your full medication list in our free Interaction Checker
Frequently Asked Questions
Can you take Finasteride and Testosterone together?
Finasteride and Testosterone have a documented contraindicated interaction. This combination is contraindicated on the FDA label. Do not take these together unless your prescriber explicitly directs it.
How serious is the Finasteride and Testosterone interaction?
It is classified as a contraindicated interaction, based on the FDA label's contraindications section (keywords: contraindications section). A contraindicated pairing generally should not be used together.
What should I do if I'm taking both Finasteride and Testosterone?
If you have been prescribed both Finasteride and Testosterone, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.
This information is educational — not medical advice.
This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.