Medically Reviewed by:

Generic Name: finasteride

Brands: Proscar, Propecia, Propecia Pro-Pak

Class: 5-alpha-reductase inhibitors

Availability: prescription required

Molecular Formula: C23H36N2O2

Substance UNII: 57GNO57U7G

What is Finasteride?

Finasteride is a 5-alpha-reductase inhibitor sold under the brand names Proscar and Propecia.

What is Finasteride Used For?

It is used for the treatment of enlarged benign prostate hyperplasia (enlarged prostate) when offered under the brand name Proscar. For benign prostate hyperplasia, the goal is to reduce symptoms associated with the condition, such as difficulty urinating. It takes six or more months to see improvement.

Propecia is for the treatment of male pattern hair loss.

How Does Finasteride Work?

It works by decreasing the production of the hormone dihydrotestosterone (DHT) in the body. DHT can trigger the enlargement of the prostate and even contribute to hair loss. Reduction of this hormone can therefore prevent prostate enlargement as well as decrease hair loss. 

How Long Does it Take for Finasteride to Work?

How long it takes to work depends on the form of the drug taken. For hair growth, it can take three to four months before the medication begins to affect. It will be six to nine months before there is significant hair regrowth.

For benign prostate hyperplasia, it takes six or more months to see improvement in relevant symptoms.

Do Not Use Finasteride If:

There are several situations where this medication may not be the right choice for you. According to the U.S National Library of Medicine, the following should not use finasteride:

  • Those who are pregnant or breastfeeding
  • Cisgender men who have had breast cancer
  • Anyone experiencing suicidal thoughts
  • Anyone with liver problems
  • Those with high-grade prostate cancer
  • People with a known allergy to 5-alpha reductase inhibitors

Please note that this list may not be complete, and there may be other situations where finasteride use is not advisable.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.


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