The facts and the myths about Finasteride side effects

There are many rumors and discussions around the hair loss drug Propecia (Finasteride) that we would like to clarify.

First, what does Propecia (Finasteride) actually do for patients?  The greatest effect of using Finasteride is on thickening partially miniaturized hair and reducing, or halting, the progression of hair loss. It is generally ineffective in re-growing hair in areas that are highly miniaturized or totally bald.

The ideal or potential candidate to use Propecia would be any male with genetic hair loss as evidenced by miniaturization of terminal hair and progressive hair loss. The earlier that treatment is started the better the chances that hair loss progression can be slowed and/or reversed.  As clinical trials have been studied in men older than 18, the decision to treat men younger than 18 would be considered off-label use and parental permission should be obtained.

Propecia has been known to be “dangerous” for women though.  Here’s the medical reason why: Finasteride is not approved or indicated for use in women. For pregnant women, exposure to significant levels of DHT in a developing male fetus may theoretically cause hypospadias, an abnormality of the male external genitalia.  Propecia tablets however are coated and will prevent contact with the actual active ingredient during normal handling, provided the tablets are not crushed, broken or ingested.

In addition, few studies using Finasteride in post menopausal women, or women not at risk for pregnancy have shown poor results using the 1mg dose, and variable results using higher dosages, thus not a successful therapy for women.

Side effects are one of the biggest discussions patients have with Finasteride. Studies in clinical trials of men ages 18-41 indicate that Finasteride side effects were less than 2% and slightly higher in men older that 41 who often have other conditions like hypertension, diabetes, and peripheral vascular disease that can predispose to sexual side effects.

The reported incidence of sexual side effects of Propecia in clinical trials is less than 2% (above placebo). The most common are reduction in libido, and erectile dysfunction.  The exact mechanism is unknown.  The testosterone (T) level is raised about 10-15% (within the normal range) and some of this extra T can be metabolized into estrogen (female) hormones, which may explain why a subset of men may experience sexual side effects. It is important to note that the incidence of erectile dysfunction in the normal adult population is 20-30% in men under 40, and increases about 10% each decade.

Because Finasteride reduces the size of the prostate, a small number of men may experience a reduction of the force or volume of ejaculation. Reduction of sperm counts has been infrequently seen in men with underlying risk factors, and generally returned to normal after discontinuation.  Breast tenderness, gynecomastia, and testicular discomfort also occurred infrequently in these trials.  Post marketing complaints of depression and persistent sexual side effects after discontinuation have been reported, but the relationship with Finasteride has not been established.

An important note, if a patient decides to discontinue using Finasteride, any gains in hair count or hair thickness will reverse, and the patient will return to the same degree of hair loss as would have developed without therapy.

When it comes to recommending a drug therapy or hair restoration, the patient’s age, degree of present and future hair loss, family history, and expectations are important factors to discuss.  If the patient may be satisfied with modest regrowth of hair, or he is young (age 25 or younger), I generally recommend Finasteride first and then wait at least one year to see its full effects.

If the patient is unlikely to be satisfied with the modest regrowth anticipated from Finasteride, or if his pattern of hair loss is such that he is unlikely to regrow hair in the affected areas (i.e., the areas have significant thinning or are totally devoid of hair), then I would consider starting Finasteride and performing a hair transplant at the same time. If Finasteride was started prior to the transplant procedure, it might reduce shedding occasionally seen post procedure, although this benefit has not been proven. (source: ISHRS, 2014)