Adverse Effects with Finasteride 5 mg/day for Patterned Hair Loss in Premenopausal Women

Sir,

Recently, Yeon's group and our own group demonstrated that the dose of 5 mg/day is effective in both pre- and post-menopausal women.[1,2] However, there are few prospective studies to determine finasteride' s adverse effects in women. Some refer to treatment of hirsutism,[3,4,5,6,7,8,9,10,11,12,13] others to acne, and few to female pattern hair loss (FPHL).[1,2] In all of them, the adverse effects reported are rare, mild, and usually transient. The most commonly referred in literature are headache, menstrual irregularities, dizziness, and increased body hair growth.[1,2]

Decreased libido was reported in 10%–20% of women with hirsutism medicated with finasteride 5 mg daily for 12 months.[5,6,7] Headache was reported in 10%–25%.[5,7] Gastrointestinal discomfort was found in 4 of 35 women.[8,9]

In women with hair loss, Kohler reported 2 out of 12 women receiving finasteride 5 mg/day complained of decreased libido, dry skin, and mild acne. We reported decreased libido in 4 of 40 postmenopausal women taking 5 mg of finasteride daily.[2] Breast swelling and tenderness,[2] headache[2] irregular menstruation[2] dizziness,[2] and increased body hair[2] have also been reported.

Carmina, Wong, Lakryc, and Shum reported the absence of important adverse effects in patients with finasteride 5 mg orally daily.[12,13] A review of 20 peer-reviewed articles found that very few side effects, or adverse events, related to sexual dysfunction have been reported in studies in which dutasteride or finasteride has been used to treat hair loss in women.

It should be emphasized that finasteride is not approved for use in women and is forbidden in pregnant women (is classified by the U. S. Food and Drug Administration as pregnancy risk Category X). Abnormalities of external male genitalia, namely, feminization of male fetus were reported in animal studies.

The aim of this study was to determine the short- and middle-term side effects of 5 mg/day finasteride in premenopausal women with FPHL.

METHODS

Inclusion criteria

Premenopausal women (18 years old or more) observed in our hair clinic between October 1, 2007 and August 31, 2011 with the diagnosis of FPHL and without treatment for the previous 6 months or having stopped treatment for 6 months. Informed consent for being treated with 5 mg/day oral finasteride. Exclusion criteria: younger than 18 years old; postmenopausal; have not signed the informed consent form; clinical or laboratory signs of hyperandrogenism; intention of being pregnant for the following 5 years; and personal or family history of breast cancer. Hepatic, cardiac, respiratory, or renal insufficiency not be willing to fulfil the plan of visits and blood collection required.

Contraception was guaranteed by mechanical barrier or drospirenone 3 mg plus ethinyl estradiol 0.03 mg tablet intake or by mechanical methods. Adverse effects were obtained by patient enquire and blood tests at months 3, 6, 12, 18, 24, and 36. A pretreatment blood test was obtained at day 0. For both finasteride (5 mg) and drospirenone (3 mg) plus ethinyl estradiol (0.03 mg), a prescription was given to the patient (not the drug itself).

Safety evaluation at 0, 3, 6, 12e 18 months: asking for symptoms and blood test-blood count, aspartate aminotransferase, alanine aminotransferase, total bilirubin, alkaline phosphatase, glycemia, urea, creatinine, total testosterone, free testosterone, dehydroepiandrosterone sulfate, delta-4 androstenedione, 5α-dihydrotestosterone, 17-beta-hydroxyprogesterone, cortisol, prolactin, luteinizing hormone, follicle-stimulating hormone.

RESULTS

From 336 patients with FPHL asked to be enrolled in the study, only 256 patients were included. After 3 months of treatment, when asked specifically for adverse effects, of the 51 patients:

One in 5 patients had one or more adverse effect at the first observation. Most of them decreased in intensity or disappeared over time. At last observation (36 months) only one in 30 patients complained of an adverse effect: 7 patients with libido reduction, 1 with hypertrichosis and 1 with mastalgia [Figure 1].

Figure 1.

Number of patients with each adverse effect over time

DISCUSSION AND CONCLUSIONS

Oral finasteride 5 mg/day seems to be a safe treatment of FPHL in premenopausal women. One in each five patients had side effects 3 months after beginning finasteride. However, they were mild and most of them reversible, even with maintenance of treatment. After 3 years of therapy, only one in 30 patients had an adverse effect.

Most of the patients with an adverse effect did not want to stop the treatment and this is in line with the perception for them of an obvious therapeutic effect described in the previous studies.[1,2]

When we compare therapeutic effect and adverse effects with a postmenopausal population,[2] we conclude that finasteride is not only more effective in premenopausal women but also adverse effects are much more common, especially in the first months of the treatment. This fact is probably due to higher levels of testosterone in premenopausal population.

We do not know why most frequent adverse effects, such as libido reduction, mastalgia or hypertrichosis/hirsutism decrease over time. Probably, there are some adaptative hormonal changes in hypophysis/gonadal axis or in brain perception.

Our main concern is the eventual existence of long-term side effects, and for that purpose, 36 months follow-up is not enough.

In conclusion, finasteride is useful in premenopausal FPHL patients that do not intend to be pregnant, especially to nonresponders or low responders to topical minoxidil (the approved treatment for FPHL). Adverse effects are frequent, mild, and tend to disappear over time, allowing the long-term treatment of the condition.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.