Is Finasteride effective in treating hair loss?

16th October 2019

Finasteride, also known under the brand name of Propecia is effective in treating male pattern baldness. It works on the crown and in the middle of the scalp. It effectively reduces the amount of DHT in hair follicles, leading to increased hair growth and slower hair loss. The hair on other parts of the body is not affected by Finasteride.

How long does it take for Finasteride to work?

It usually takes from six to nine months to see the full effects of Finasteride. This is because hair follicles need lots of time to produce new hair. Finasteride does start to work immediately at blocking DHT. On average, it will reduce the amount of DHT in the body by 70%.

Will Finasteride allow me to regrow hair?

Normally, hair follicles undergo a cycle of growth, shedding, and dormancy. This is a natural health cycle, even in individuals with healthy heads of hair. As such, it can take a long time for hair to regrow, as follicles may be in the dormant cycle when DHT is lowered, and won't begin regrowing until the follicle completes its cycle. For this reason, you may not see the full effects of Finasteride until after six to nine months of use. Many men will see a more immediate result in preventing hair from being lost in the first place. As the DHT levels will be quickly lowered in the body, hair loss due to the presence of DHT should significantly slow.

The three phases of hair growth

There are three phases of hair growth; anagen, catagen, and telogen. They can be paraphrased as "growth", "renewal" and "rest". It is important to know the cycles of hair growth if you wish to understand why Finasteride takes so long to be effective.


Anagen is the growth phase of hair follicles. Hairs usually remain in this state from between two to six years. The longer the cycle lasts, the longer your hair can get. At any given time, approximately 80% to 85% of hairs are in this phase.


The Catagen phase of renewal only lasts two weeks. This lets the follicle renew itself.


The dormant phase of telogen lasts around one to four months. Around 12% to 20% of hair follicles are in this phase at any given time. At the end of the telogen phase, the existing hair is pushed out and the anagen phase begins once again.

What is hair loss?

This seems to be a silly question, of course, hair loss is when an individual loses hair. Specifically, the process of hair loss includes shrinking hair follicles which begin to experience longer telogen phases and shorter anagen phases. This process is induced by the chemical DHT.

What is DHT?

DHT is dihydrotestosterone. It is thought to cause hair follicles to miniaturize, preventing the growth of hair. By the age of 50, half of men will probably lose some hair due to DHT. You may have noticed that bodybuilders can experience a higher rate of hair loss. The use of anabolic drugs elevates the presence of DHT in their bodies.

Why does hair still grow on the armpit or beard areas but not on the scalp?

DHT on the scalp shrinks hair follicles. On the scalp, hair grows better without the presence of DHT (in men with male pattern baldness). However, in other areas of the body, hair growth is promoted by DHT. For reasons that are not well understood, DHT is essential for most hair growth, but not hair on the scalp. A study in 1998 found that hair follicles on the head have more androgen receptors on them than follicles on other areas of the body. The extent of receptors seems to be passed on as a genetic trait, where some individuals have more than others. Those with low receptors on their head usually do not experience male pattern baldness.

Can Finasteride prevent prostate cancer?

In short, Finasteride is not typically prescribed in the treatment of prostate cancer. There was a massive Prostate Cancer Prevention Trial that took place over 25 years. This study randomized 18,882 men between 1993 and 1997 to either Finasteride or a placebo.

The study found that Finasteride reduced prostate cancer in men by a whopping 25%. Unfortunately, the same study found that finasteride treatment had a small increase in high-grade prostate cancers, thus earning the drug a black box warning. However, years later, there was a followup that attempted to determine if there were statistically more deaths due to prostate cancer with finasteride treatment.

It was found there were 42 deaths due to prostate cancer to those who used Finasteride, compared to 56 on the placebo. Thus, there was not a significant increase in deaths due to finasteride use. Finasteride is not normally prescribed in the treatment of prostate cancer. There are potential side effects when using Finasteride, such as impotence and urinary incontinence.

What are the more serious side effects of Finasteride?

Side effects of finasteride include decreased sex drive and ejacuation problems.

In well-conducted research trials, sexual side effects occurred in about 4% to 6% of men, and these effects were usually reversible.
In April 2012, the FDA issued a warning on finasteride. It stated that sexual side effects could persist even after stopping the medication. Those side effects include decreased sex drive and ejaculation problems. The warning was based on about 100 reports the FDA received over nearly 20 years. This is not proof that finasteride was to blame since a variety of medical conditions and prescription drugs could explain the sexual symptoms the men reported while taking finasteride.