Finasteride is a daily oral medication that lowers levels of dihydrotestosterone (DHT), a hormone involved in prostate growth and male pattern hair loss. It is sold as 1 mg tablets for hair loss and 5 mg tablets for benign prostatic hyperplasia (BPH). Knowing how the dose, expected timeline, and side effects differ between the two uses helps you take it confidently.
What Finasteride Does
Finasteride blocks an enzyme (5-alpha-reductase type II) that converts testosterone to DHT.
DHT is a primary driver of prostate enlargement in BPH and of androgenetic (male pattern) hair loss.
Lower DHT shrinks the prostate over months and slows or partially reverses hair loss in genetically susceptible men.
Finasteride does not lower testosterone levels significantly. It works upstream on the conversion to DHT.
How to Take It
Hair loss: 1 mg once daily, with or without food. Same time each day improves consistency.
BPH: 5 mg once daily. Often combined with an alpha-blocker (tamsulosin or alfuzosin) in the first months for symptom relief while finasteride takes effect.
Hair loss benefit usually requires 3 to 6 months of daily dosing to see slowing of loss; full effect can take 12 months.
BPH symptom improvement typically becomes noticeable at 3 to 6 months and full effect at 6 to 12 months.
Stopping finasteride causes the benefit to reverse over 6 to 12 months. Hair regained on the medication will gradually shed again if stopped, and prostate volume slowly returns to baseline.
Common Side Effects and Safety
Sexual side effects (decreased libido, erectile dysfunction, decreased ejaculate volume) occur in roughly 1 to 4 percent of users in clinical trials. Most resolve after stopping; rare reports of persistent symptoms exist.
Breast tenderness or breast tissue growth can occur and should be reported. Rare cases of male breast cancer have been reported in patients on 5-alpha-reductase inhibitors.
Mood changes, including depression, have been reported. Tell your prescriber if you notice low mood, anhedonia, or sleep changes.
Pregnancy alert: Finasteride can cause genital abnormalities in a male fetus. Women who are pregnant or could become pregnant should not handle broken or crushed tablets. Whole tablets have a coating that prevents skin exposure.
Finasteride lowers PSA (prostate-specific antigen) by about half. Tell any provider checking PSA that you take finasteride so the lab value can be interpreted correctly.
When to Stop or Discuss
Persistent sexual side effects, mood changes, or breast changes are reasons to discuss alternatives with your prescriber.
Before any prostate biopsy or PSA test, remind the team that you take finasteride.
If you are switching to dutasteride (Avodart), the dose is 0.5 mg daily and the side effect profile is similar.
Finasteride does not protect against prostate cancer entirely; some studies suggest it lowers risk of low-grade prostate cancer but may slightly increase detection of higher-grade tumors. Discuss screening with your urologist.
Frequently asked
Questions patients ask.
Will hair I have already lost grow back on finasteride?
Some hair may return, particularly hair lost recently. Long-standing bald areas usually do not regrow significantly. Most men see slowing or stopping of further loss as the main benefit, with modest regrowth at the crown and mid-scalp.
Can women take finasteride?
Premenopausal women generally should not take finasteride because of the risk of birth defects in a male fetus. Some prescribers use it off-label in postmenopausal women for hair loss with appropriate counseling. This is a specialty conversation rather than a routine prescription.
Does finasteride cause permanent sexual problems?
Sexual side effects in clinical trials were reversible in most men. Persistent post-finasteride symptoms have been reported in a small number of users; the condition is debated in the medical literature. If you experience side effects, raise them early with your prescriber rather than waiting.
For patients
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This guide provides general information. For instructions tailored to your specific procedure, ask your provider about QR Rx care plans.
These medication guides are for educational purposes only and do not replace medical advice. Always follow your healthcare provider's specific medication instructions.
