What is the primary treatment for a female patient presenting with idiopathic hirsutism?

Primary Treatment for Idiopathic Hirsutism

Combined oral contraceptives (OCCs) are the first-line pharmacological treatment for idiopathic hirsutism, and if response is inadequate after 6-9 months, add spironolactone 100-150 mg daily as antiandrogen therapy. 1, 2

Understanding Idiopathic Hirsutism

Idiopathic hirsutism represents less than 20% of all hirsutism cases and is defined by excess terminal hair growth in a male pattern with normal ovulatory function and normal circulating androgen levels. 3 The pathophysiology involves increased skin 5α-reductase activity converting testosterone to dihydrotestosterone (DHT) locally in hair follicles, rather than systemic androgen excess. 3

Critical diagnostic point: A history of regular menses alone is insufficient to diagnose idiopathic hirsutism, as up to 40% of eumenorrheic hirsute women are actually anovulatory. 3 True idiopathic hirsutism requires documented normal ovulation and normal androgen levels.

Treatment Algorithm

Step 1: Lifestyle Modification (If Applicable)

• Weight loss of as little as 5% of total body weight significantly improves hirsutism through testosterone reduction, targeting an energy deficit of 500-750 kcal/day combined with regular exercise. 1
• This reduces Ferriman-Gallwey scores by a mean difference of -1.19 points. 1

Step 2: First-Line Pharmacotherapy

• Start combined oral contraceptives containing non-androgenic progestins (avoid norethisterone derivatives or levonorgestrel). 1, 4, 2
• Third-generation OCCs have restricted effectiveness short-term (6 cycles) but cure mild-to-moderate hirsutism and improve severe hirsutism with long-term use (>12 cycles). 5
• OCCs work by suppressing ovarian androgen production and increasing sex hormone-binding globulin, which reduces free testosterone. 1, 5

Step 3: Add Antiandrogen Therapy

• If inadequate response after 6-9 months of OCC monotherapy, add spironolactone 100-150 mg daily. 1, 2
• Spironolactone achieves improvement in 85% of patients with complete remission in 55%. 1
• Alternative antiandrogens include cyproterone acetate (12.5-50 mg/day in reverse sequential regimen) or flutamide (250-500 mg/day), which are highly effective. 5, 6
• Finasteride 5 mg/day is the least effective antiandrogen but has minimal adverse effects. 5

Important caveat: Pregnancy must be strictly avoided during antiandrogen therapy due to risk of abnormal male fetal development. 5 OCCs provide essential contraception when using antiandrogens. 5, 7

Step 4: Adjunctive Cosmetic Therapy

• Laser hair removal is an essential adjunct to systemic therapy, requiring multiple treatments for optimal results. 1, 8
• Laser therapy must be combined with medical management to address the underlying pathophysiology, as it treats symptoms rather than the cause. 8
• Topical eflornithine hydrochloride cream can be a useful adjuvant when used with systemic medications or laser therapy. 4, 2

Timeline for Response

• Expect hirsutism reduction in 6-12 months with pharmacological therapy. 4
• Clinical improvement should be monitored at 3-6 month intervals. 4

When NOT to Use Metformin

• Metformin monotherapy is NOT recommended for idiopathic hirsutism. 1
• Metformin should only be used when metabolic abnormalities such as insulin resistance or prediabetes coexist with hirsutism. 1, 2
• There is no convincing evidence that insulin sensitizers are effective for hirsutism alone. 2

Common Pitfalls to Avoid

• Do not use OCCs containing androgenic progestins, as they worsen hirsutism. 4
• Do not rely on regular menses alone to diagnose idiopathic hirsutism without confirming normal ovulation. 3
• Do not expect rapid results—systemic therapy requires 6-12 months for meaningful improvement. 4
• Do not use antiandrogens without adequate contraception. 5, 7