Androgenetic alopecia

Male Pattern Hair Loss

There are two medications currently approved by the US Food and Drug Administration (FDA) for the treatment of MPHL: topical minoxidil (2% solution, 5% solution, and 5% foam formulations), and finasteride 1 mg once daily. Low-level laser light therapy medical devices also have FDA 510(k) clearance for the treatment of AGA. All other medical treatment options discussed below are used off-label. Treatments need to be continued indefinitely for continued effect.

Topical minoxidil is an effective therapy for AGA, with minimal side effects (e.g., irritant contact dermatitis, which is more likely with solution compared to foam). Minoxidil is converted by sulfotransferase in the ORS of hair follicles into its active metabolite, minoxidil sulfate. Minoxidil prolongs anagen duration, shortens telogen duration, and reverses hair follicle miniaturization. Inter-individual differences in the percutaneous absorption and sulfotransferase levels account for the variable clinical response. For men, the recommended dose of minoxidil 5% solution (50 mg/mL) is 1 mL twice daily. Peak hair growth is seen between 26 and 52 weeks. Some clinical improvement is noted after 2 years of continuous use in 40%–60% of patients. The vertex responds better than the frontal scalp. Continued use is necessary for sustained efficacy, and patients may experience a significant hair shedding 2–3 months after stopping treatment. For topical minoxidil 5% foam, the recommended usage is half a capful twice daily.

Minoxidil has also been used orally off-label. It has a higher patient treatment adherence rate compared to topical application. It is particularly useful for patients who develop contact dermatitis to topical minoxidil. Doses of 0.25–5 mg once daily have been evaluated in various studies for both MPHL and FPHL and found to be useful. Potential side effects are dose-related and include postural dizziness, palpitations, fluid retention, and hypertrichosis. Finasteride is a 5α-reductase type II isoenzyme competitive inhibitor that is FDA-approved for the treatment of MPHL. Finasteride 1 mg daily reduces serum DHT by 71.4% and scalp DHT by 64.1% after 6 weeks in one study, while serum DHT is reduced by 68.4% after 52 weeks in another. On the other hand, finasteride 5 mg daily reduces serum DHT by 72.2% and scalp DHT by 69.4% after 6 weeks in one study, while serum DHT is reduced by 73% and scalp DHT by 41% after 24 weeks in another. Its actions include reversal of hair follicle miniaturization and prolonging anagen duration. Continuous use for 2 years arrests hair loss in over 95% of men, with 66% achieving moderate hair regrowth and 5% marked hair regrowth. Following discontinuation of finasteride, patients’ hair counts return to baseline within 1 year. Finasteride is generally well tolerated. Sexual side effects such as decreased libido, erectile dysfunction, and decreased seminal fluid volume have been reported in 1.5% of men while on treatment, which usually reverse within 3 months of treatment cessation. Other less common side effects include gynecomastia and depression. Dutasteride has also been used off-label to treat MPHL. Dutasteride is a type I and type II 5α-reductase isoenzyme inhibitor with greater suppression of DHT production than finasteride. Serum DHT is reduced by 92% and scalp DHT by 51% with dutasteride 0.5 mg daily for 24 weeks. In a meta-analysis, dutasteride has been shown to be more effective than finasteride in MPHL treatment. Dutasteride also produces greater adverse sexual side effects than finasteride.

Female Pattern Hair Loss

Topical minoxidil is the FDA-approved treatment for FPHL. Women may use the 2% solution twice daily, or 5% foam or solution once daily. Clinical improvement is seen in up to 80% of patients. Topical minoxidil is well tolerated. Potential side effects include facial hypertrichosis, scalp pruritus, palpitations, postural dizziness, or headaches in women with low blood pressure. While oral minoxidil has been used to treat pre-eclampsia in pregnancy in doses up to 100 mg daily, use of topical minoxidil to treat hair loss is generally not recommended for women while pregnant. Oral minoxidil has also been used off-label to treat FPHL in doses of 0.25–5 mg daily. It is particularly useful for women who develop scalp irritation with topical minoxidil and for women with long hair who find it difficult to adhere to topical therapy.

A number of oral antiandrogens have also been used off-label to treat FPHL. These agents appear to be more effective in women with hyperandrogenism. Androgen receptor antagonists used include spironolactone, cyproterone, flutamide, and bicalutamide. The 5α-reductase inhibitors finasteride and dutasteride have also been used to treat FPHL; however, they appear to be less effective than androgen receptor antagonist agents. Anti-androgens and 5α-reductase inhibitors could potentially feminize an unborn male fetus and caution is required when using in women with childbearing potential. Spironolactone has been shown to arrest progression of FPHL in over 90% of women, with approximately 30% having hair regrowth. This can be given at a dose of 100–200 mg once daily. Potential side effects include breast tenderness, menstrual irregularities, headaches, decreased libido, polyuria, and hyperkalemia. There is no need for routine monitoring of serum potassium levels in a healthy female with no kidney disease. Cyproterone acetate has been used at a dose of 50–100 mg once daily for the first 10 days of the menstrual cycle in premenopausal women and continuously or for 3 weeks per month in postmenopausal women. Potential side effects include weight gain, breast tenderness, and decreased libido. Flutamide is a potent antiandrogen that can be used at doses of 50–250 mg for the treatment of FPHL not responding to other medical treatment modalities. Rare but severe cases of hepatoxicity have been reported; hence, regular monitoring of liver function tests is mandatory. Other potential side effects include diarrhea and hot flushes. Bicalutamide is an antiandrogen in the same family as flutamide but is less likely to cause hepatoxicity and has fewer other side effects. Effective doses used include 10–50 mg once daily.

Finasteride has been used off-label in the treatment of FPHL. Studies in premenopausal and postmenopausal women have reported effective dosing between 1.25 mg and 5 mg once daily. Potential side effects include decreased libido and risk of teratogenicity.

Hair restoration surgery is effective in patients who do not respond satisfactorily to medical therapy and in whom the hair loss is advanced. Skilled hair transplant surgeons can create a natural hair line and achieve a cosmetically significant increase in hair density. The technique requires substantial additional training and there is significant doctor to doctor variation in the quality of the outcome.

Other possible adjunctive treatments include platelet-rich plasma (PRP) treatment, low-level laser light therapy, microneedling, fractional lasers, topical prostaglandin analogs , and Stemoxydine . Further research is required to understand the true potential of these modalities. Keratin fiber camouflage powders, hairpieces, and wigs are also helpful for camouflage.