What causes excessive hair growth in women, such as growing a beard, and how is it treated?

Conditions Causing Beard Growth in Women

Polycystic ovary syndrome (PCOS) is the primary cause of beard growth in women, accounting for 70-80% of hirsutism cases, followed by idiopathic hirsutism which represents 5-15% of cases. 1, 2

Primary Causes

Polycystic Ovary Syndrome (PCOS) is the dominant etiology, characterized by hyperandrogenic chronic anovulation with insulin resistance and hyperinsulinemia leading to excessive androgen production. 1 This affects approximately 4-6% of women in the general population. 1

Idiopathic hirsutism occurs when women have normal ovulatory function and normal androgen levels despite excessive hair growth, representing the second most common cause. 2, 3

Less common but important causes include:

• Non-classical congenital adrenal hyperplasia (21-hydroxylase deficiency) 1
• Androgen-secreting tumors of the ovary or adrenal glands 1
• Cushing's syndrome 1
• Medications including exogenous androgens and certain antiepileptic drugs 1
• Hyperprolactinemia and thyroid disorders 3

Diagnostic Approach

Clinical assessment should focus on:

• Distribution and severity of hair growth using the Ferriman-Gallwey scoring system 3
• Menstrual history (oligomenorrhea or amenorrhea suggests PCOS) 1
• Associated signs including acne, androgenetic alopecia, and clitoromegaly 1, 4
• Signs of insulin resistance such as obesity and acanthosis nigricans 1
• Rapid onset over weeks to months (suggests androgen-secreting tumor) 3

Laboratory testing is warranted when hirsutism occurs with other hyperandrogenic signs:

• Total testosterone or free testosterone (levels >200 ng/dL suggest androgen-secreting tumor) 1
• DHEA-S and androstenedione 1, 4
• Thyroid-stimulating hormone and prolactin 1
• Glucose/insulin levels 1

The American Academy of Dermatology notes that routine endocrinologic testing is not indicated for mild hirsutism without other signs of hyperandrogenism. 1

Pelvic ultrasound can detect polycystic ovaries (>10 peripheral cysts, 2-8 mm diameter, with thickened ovarian stroma) in women with suspected PCOS. 1

Treatment Algorithm

First-line pharmacologic therapy:

Combined oral contraceptives are recommended as first-line treatment for PCOS-related hirsutism to suppress ovarian androgen production. 5, 1 Avoid OCPs containing androgenic progestins such as norethisterone derivatives or levonorgestrel as they can worsen hirsutism. 1

Anti-androgen medications can be added or used as monotherapy:

• Spironolactone is widely used but carries risks of hyperkalemia (monitor serum potassium within 1 week of initiation), hypotension, electrolyte abnormalities, and gynecomastia in a dose-dependent manner 6
• Finasteride may be particularly beneficial for adolescents with PCOS and endocrine comorbidities 1
• Flutamide and cyproterone acetate are alternatives 5, 1

Topical eflornithine hydrochloride cream is the only FDA-labeled agent specifically for hirsutism treatment. 5

Insulin-sensitizing agents (metformin) may improve ovulation and reduce androgen levels in women with PCOS. 1

Weight loss of as little as 5% of initial body weight can improve metabolic and reproductive abnormalities in PCOS. 5, 1

Important Caveats

Treatment requires at least 6 months before switching therapies due to the length of the hair growth cycle. 3

Combined medical interventions are most effective, typically combining an antiandrogen with an ovarian suppression agent. 5

Adequate contraception is mandatory when using antiandrogens due to potential teratogenic effects. 7

Cosmetic measures (shaving, waxing, electrolysis, laser therapy) are often necessary as systemic therapy reduces hair growth in less than 50% of cases. 5, 7

Women with rapid onset hirsutism or signs of virilization require urgent evaluation for androgen-secreting tumors. 3