Finasteride for Hair Loss: The Side Effects

Androgenic alopecia, more commonly known as male-pattern balding, is mediated through the effects of male hormones. The most effective approach to stopping and reversing male-pattern balding is to block the action of these androgenic hormones in some way. One of the best-known treatments for male-pattern balding is a drug called finasteride (Propecia).

Finasteride (Propecia), an enzyme inhibitor

finasteride ru58841.infoFinasteride is sold under the brand names Propecia and Proscar. It is taken as an oral tablet. Once in the body, it acts to block the action of the enzyme 5-alpha-reductase. 5-alpha-reductase is expressed in certain parts of the body, such as the prostate and the hair follicles. When systemic testosterone reaches cells that express 5-alpha-reductase, the enzyme converts the testosterone into a much more potent androgenic hormone called dihydrotestosterone (DHT). The activity of DHT in the hair follicles is what causes androgenic alopecia. By preventing the production of DHT, finasteride can effectively stop the hair-loss process.

A systemic, orally administered medication

The problem with finasteride is that it does not just target the hair follicles. Users of the drug expose their entire body to its DHT-blocking activity. in fact, finasteride is often used to treat benign prostate hyperplasia as well as hair loss because it blocks the activity of 5-alpha-reductase everywhere. Unfortunately, this systemic effect can and does cause significant side effects in users.

Sexual side effects

Not surprisingly, blocking the production of an important male sex hormone can produce significant sexual side effects. Men using finasteride commonly report reductions in sexual interest, drive and libido (1, 2). Some experience erectile dysfunction, and many experience reduced sexual performance. Decreased semen production, abnormal ejaculation, and even infertility can also occur (2, 3). Since many users of finasteride for hair loss are younger men of prime reproductive age, these side effects can significantly impair quality of life and may interfere with plans to start a family and introduce stress and discord into relationships.

Non-sexual side effects

In addition to sexual side effects, finasteride can cause other unpleasant conditions. Confusion and “brain fog” are commonly reported by users. Dizziness, chills, and drowsiness are also commonly reported (1). Some people feel nauseated, have headaches, experience swelling of the face and extremities, or develop itchy skin. Breast enlargement and rapid weight gain are not uncommon. Some users report pain in the testicles, back, or abdomen. More alarmingly, finasteride use may increase the risk of developing male breast cancer, and it can also increase the risk of developing a very aggressive and deadly type of prostate cancer (4).

The side effects may be permanent

Because not all users of finasteride experience side effects, many men may be tempted to “just try it” and see if, for them, the balance between side effects and beneficial effects on hair loss is acceptable. If the side effects are too severe, they figure they can simply stop taking the drug. However, some side effects may not go away after discontinuing finasteride. Men who develop erectile dysfunction and other sexual problems due to finasteride may not improve after stopping its use (2, 3).

A non-systemic option

A better approach to treating hair loss is to only target the site of the problem, the hair follicles. RU58841 is a highly effective androgen blocker that is applied directly to the scalp. Because it does not enter the body in any significant concentration, it has no systemic side effects. RU58841 is clearly a better choice for treating androgenic alopecia.


(2) Indian Dermatol Online J. 2012 Jan-Apr; 3(1): 62–65. Finasteride and sexual side effects
(3) N Engl J Med. 1992 Oct 22;327(17):1185-91. The effect of finasteride in men with benign prostatic hyperplasia. The Finasteride Study Group.
(4) N Engl J Med. 2003 Jul 17;349(3):215-24. Epub 2003 Jun 24. The influence of finasteride on the development of prostate cancer.

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