Unwanted Hair (Hypertrichosis and Hirsutism): Causes, Diagnosis and Treatment — Overview, Diagnosis & Treatment Options | MyMedicPlus

Unwanted hair growth is classified into two distinct clinical entities: hirsutism — androgen-dependent male-pattern terminal hair growth in women — and hypertrichosis — diffuse or localized excess hair growth unrelated to androgen excess, affecting both sexes. Hirsutism affects 5–10% of women of reproductive age and is defined by a modified Ferriman-Gallwey (mFG) score of 8 or higher (score range 0–36 across 9 androgen-sensitive body sites including upper lip, chin, chest, upper and lower abdomen, thighs, and upper arms). Polycystic ovary syndrome (PCOS) accounts for 70–80% of hirsutism cases. Hypertrichosis may be congenital (rare genetic disorders such as hypertrichosis universalis) or acquired (drugs, malnutrition, or paraneoplastic). The psychological burden of unwanted hair — particularly facial hair in women — is substantial, causing significant distress, reduced quality of life, and social avoidance. Both laser hair removal and hormonal treatments offer effective long-term management options.

Hirsutism results from excess androgen production or heightened end-organ sensitivity of the pilosebaceous unit to androgens. PCOS (characterized by oligo/anovulation, clinical/biochemical hyperandrogenism, polycystic ovarian morphology) is the dominant cause. Idiopathic hirsutism — normal androgen levels with increased 5-alpha-reductase activity at the hair follicle — occurs in 5–15% of hirsute women. Less common causes include congenital adrenal hyperplasia (CAH, especially non-classic 21-hydroxylase deficiency), Cushing's syndrome, androgen-secreting adrenal or ovarian tumors, and thyroid disorders. Drug-induced hirsutism is caused by danazol, anabolic steroids, progestogens with androgenic activity (levonorgestrel, norethindrone), and ciclosporin. Acquired hypertrichosis is associated with minoxidil, phenytoin, ciclosporin, and paraneoplastic syndromes (hypertrichosis lanuginosa acquisita — associated with GI cancers). Ethnicity strongly influences hair follicle androgen sensitivity; Mediterranean, South Asian, and Middle Eastern women have higher baseline mFG scores.

Hirsutism presents as coarse, dark terminal hair growth on androgen-sensitive areas: upper lip, chin, sideburns, neck, chest, areolae, linea alba, inner thighs, and lower back. The mFG scoring system quantifies severity: mild (8–14), moderate (15–24), and severe (25–36). Associated symptoms of PCOS include irregular or absent menstrual periods, acne, scalp hair thinning (androgenic alopecia), and weight gain. Rapid onset of hirsutism — weeks to months — combined with virilization (clitoromegaly, voice deepening, temporal balding) suggests an androgen-secreting tumor and requires urgent evaluation. Acanthosis nigricans (velvety hyperpigmentation of the neck and axillae) indicates insulin resistance. Hypertrichosis presents as generalized lanugo-type or vellus hair growth not following androgen-distribution patterns; paraneoplastic hypertrichosis lanuginosa presents as fine, silky, unpigmented hair covering the face and trunk.

Clinical assessment using the modified Ferriman-Gallwey score quantifies hirsutism severity and tracks treatment response. Laboratory evaluation includes total and free testosterone, DHEA-S (adrenal androgen marker), 17-hydroxyprogesterone (screening for non-classic CAH — morning follicular-phase level; if elevated, ACTH stimulation test), prolactin, TSH, and fasting glucose/insulin (HOMA-IR for insulin resistance). LH:FSH ratio >2:1 supports PCOS diagnosis. Rotterdam criteria (2 of 3: oligo/anovulation, hyperandrogenism, polycystic ovaries on ultrasound) are used for PCOS diagnosis per Endocrine Society guidelines. Pelvic/transvaginal ultrasound evaluates ovarian morphology and excludes an adrenal or ovarian mass. When total testosterone >150 ng/dL or rapid virilization occurs, adrenal/ovarian imaging (CT or MRI) and dexamethasone suppression test are required to exclude secreting tumors. Skin biopsy is rarely needed.

Management integrates cosmetic hair removal with treatment of the underlying hormonal cause. Laser hair removal — targeting melanin in the hair follicle — is the most effective long-term cosmetic option. Long-pulsed Nd:YAG (1064 nm) is the safest for darker skin types (Fitzpatrick IV–VI); alexandrite (755 nm) and diode (800–810 nm) lasers are preferred for fair to medium skin. Multiple sessions (typically 6–8) spaced 4–8 weeks apart are required; permanent reduction of 70–90% is achievable. Electrolysis (galvanic, thermolytic, or blend) is the only FDA-cleared method for permanent hair removal — suitable for light or white hairs not targeted by laser. Anti-androgen therapy for hirsutism: spironolactone 100–200 mg/day (blocks androgen receptors and reduces 5-alpha-reductase) is first-line medical treatment per Endocrine Society guidelines, combined with a combined oral contraceptive pill (COC) for menstrual regulation and contraception (spironolactone is teratogenic). Eflornithine 13.9% cream (Vaniqa) inhibits ornithine decarboxylase, reducing facial hair growth by 60% as topical adjunct. Finasteride 5 mg/day is an alternative anti-androgen. Metformin improves hirsutism in PCOS by reducing insulin resistance and androgen production.

The prognosis for hirsutism and unwanted hair growth depends largely on the underlying cause, the treatment modality selected, and adherence to ongoing management. PCOS-related hirsutism — the most common cause — can be effectively managed but rarely cured; ongoing medical treatment (oral contraceptive pills, spironolactone) or cosmetic hair removal is required long-term. Weight loss of 5–10% in overweight women with PCOS significantly improves testosterone levels and may reduce hirsutism severity over 6–12 months. Idiopathic hirsutism typically persists without treatment but is managed effectively with anti-androgen therapy and laser hair removal. Tumor-related hirsutism (adrenal or ovarian androgen-secreting tumor) resolves completely after successful surgical resection. Laser hair removal achieves 70–90% permanent hair reduction in most patients after 6–8 sessions, with outcomes best maintained when underlying hormonal causes are also controlled. Drug-induced hirsutism resolves after discontinuation of the causative agent, usually within 6–12 months. Electrolysis provides permanent removal for individual hairs but is time-intensive. The psychological impact of unwanted hair — particularly facial hair in women — is significant; effective treatment markedly improves quality of life, self-confidence, and social functioning. Monitoring parameters include modified Ferriman-Gallwey score response, androgen levels, and subjective symptom burden reassessed at 6-monthly intervals during active treatment.

Hirsutism cannot be fully prevented, but lifestyle modification in PCOS reduces androgen levels and improves hirsutism over time. Weight loss of 5–10% body weight in overweight women with PCOS significantly reduces testosterone levels, restores menstrual regularity, and may improve hirsutism. Regular aerobic exercise and a low-glycemic-index diet reduce insulin resistance, a key driver of PCOS-associated hyperandrogenism. Avoiding anabolic steroids and androgenic progestogens prevents drug-induced hirsutism. Drug-induced hypertrichosis can be avoided by using alternative medications when possible. Patients initiating minoxidil should be counselled about hypertrichosis as a predictable side effect.

Seek urgent medical evaluation for rapid onset of hirsutism — developing over weeks to months — particularly if accompanied by signs of virilization: clitoromegaly, voice deepening, temporal hair recession, or muscle hypertrophy. These features strongly suggest an androgen-secreting adrenal or ovarian tumor requiring prompt imaging. Any woman with hirsutism and irregular periods, acne, or difficulty conceiving should be evaluated for PCOS and other endocrine causes. An endocrinologist should be consulted when total testosterone exceeds 150 ng/dL, DHEA-S is markedly elevated, 17-hydroxyprogesterone is abnormal, or when first-line treatments fail. Women planning pregnancy while on anti-androgen therapy (spironolactone, finasteride) must stop treatment well before conception due to risk of feminization of a male fetus.