Hirsutism in Babies, Kids and Teens: What’s Normal and When to Worry

Short answer: True hirsutism is rare in babies and young children. Most hair you notice on a baby is normal fine hair, and early pubic or underarm hair in a young child is often premature adrenarche, a usually harmless early rise in adrenal hormones. Still, any pubic, underarm or coarse body hair before age 8 in a girl should be checked by a pediatrician. In teenagers, new facial or body hair is usually part of normal puberty, but heavy hair growth with irregular periods can be a sign of PMOS (formerly PCOS).

Noticing unexpected hair on your child can be worrying. This guide walks through what is normal at each age, from babies to teenagers, which signs need a doctor’s visit and what the main causes and treatments are. If you are a teen reading this for yourself, the sections on puberty and PMOS are for you.

Hair in babies: what is normal?

Before birth, babies are covered in lanugo, a fine, soft, unpigmented hair. It is normally shed around eight months into pregnancy and replaced by vellus and terminal hair.^[1] That is why babies born early are more likely to still have some fine body hair.

Excess hair all over the body from birth is called congenital hypertrichosis. It is rare and is believed to be genetic.^[1] It is different from hirsutism, which is male-pattern hair driven by androgens. Read more in hirsutism or hypertrichosis?

Hormone exposure can also cause early hair. The Pediatric Endocrine Society notes that contact with hormone products such as testosterone gels can cause early pubic hair in children.^[2] If anyone at home uses a testosterone or estrogen gel or cream, wash your hands after applying it and keep children away from treated skin, and tell your pediatrician. Some medicines, including minoxidil, can also increase body hair.^[1]

Before puberty: early pubic hair, body odor and acne

Premature adrenarche

The adrenal glands make weak androgens, mainly DHEA-S. In some children, these rise earlier than usual. This is called premature adrenarche, and it is a common reason a young child develops pubic or underarm hair before age 8 in girls or 9 in boys. It can also bring adult-type body odor and acne. Importantly, girls with premature adrenarche do not have breast development.^[2]

Premature adrenarche does not directly cause health problems, and it usually needs no medical treatment. Medicines used for true early puberty do not affect adrenal hormones, and no treatment removes the pubic or underarm hair. Deodorant is safe to use.^[2] Some girls with premature adrenarche may have a higher risk of developing PMOS as teenagers, and healthy eating and regular exercise may lower that risk.^[2]

Precocious puberty

Precocious puberty means puberty that starts before age 8 in girls or age 9 in boys.^[3] In girls, the signs include breast development, a growth spurt and early periods.^[5] In most cases no underlying cause is found, and puberty has simply started early.^[4][5] Less often, it is caused by a brain abnormality, a tumor of the ovary or adrenal gland, a rare genetic syndrome such as McCune-Albright syndrome, severe hypothyroidism, congenital adrenal hyperplasia or exposure to hormone creams or medicines.^[4]

Early puberty can sometimes lead to shorter adult height because growth stops too soon, and it can cause anxiety about being different from friends.^[3][5] If the cause is central precocious puberty, which starts in the brain, a pediatric endocrinologist may offer treatment.

Non-classic congenital adrenal hyperplasia

A small percentage of children with early pubic hair have a mild, inherited form of congenital adrenal hyperplasia (CAH).^[2] In the non-classic form, the adrenal glands make extra androgens. It is estimated to affect about 1 in 1,000 people, and in women it can later cause hirsutism, irregular periods and scalp hair loss.^[6] It is diagnosed with blood tests.

How doctors check a child with early hair growth

A pediatrician or pediatric endocrinologist will usually start with a history and examination, including the child’s growth chart. Further tests vary, but may include:^[2][5]

• Blood tests for adrenal hormones such as DHEA-S, and for pubertal hormones such as LH, FSH, estradiol and testosterone
• A bone age X-ray of the hand and wrist, which shows how far the skeleton has matured
• A brain MRI if the results point to central precocious puberty

Many doctors focus testing on children who are growing very fast or have breast or genital development, since these point away from simple premature adrenarche.^[2]

Treatment in younger children

Evidence: Strong Treatment depends on the cause. For central precocious puberty, medicine can pause puberty by suppressing the pituitary hormones LH and FSH. It is given as a monthly or three-monthly injection or a yearly implant, and may give a child more time to grow.^[5] For premature adrenarche, no medical treatment is usually needed.^[2] Rare causes such as tumors need treatment of the underlying problem.

If hair bothers your child, gentle options such as trimming underarm hair with small scissors are safe.^[2] Keep the focus on comfort rather than appearance, and let your child lead on whether hair removal matters to them.

Hirsutism during puberty

During puberty, rising adrenal androgens normally cause underarm hair, pubic hair and body odor.^[7] Many teens also notice darker hair on their arms, legs or upper lip, which is often normal. Androgen levels in most teens reach the adult range between 12 and 15 years of age.^[8]

High androgen levels can cause more hair growth than usual, on the face, chin, neck, chest, breasts, back or stomach.^[7] A common cause in teens is PMOS, previously called polycystic ovary syndrome (PCOS). It was renamed in 2026 after a global consensus to reflect its effects on several hormone systems and metabolism.^[9]

Why PMOS is harder to diagnose in teens

Periods are often irregular for the first two to three years after a girl’s first period, so irregular cycles alone are not a reliable sign of PMOS in early adolescence.^[7] The International PCOS Guideline uses age-specific definitions of irregular cycles for teens, does not recommend ovarian ultrasound for diagnosis in adolescents and advises against using the anti-Müllerian hormone (AMH) blood test in this age group yet.^[8]

Teens who have some features of PMOS but do not meet the full criteria can be considered “at increased risk” and reassessed later, at or before eight years after their first period.^[8] The Pediatric Endocrine Society stresses that symptoms such as unwanted hair and acne can be treated even before a firm diagnosis.^[7]

Treatment for teens with hirsutism

The combined pill

Evidence: Strong The International PCOS Guideline says the combined pill can be considered for teens with PMOS or at risk of it, to treat hirsutism or irregular periods.^[8] Hormone treatment works slowly. It takes about six months to see an effect on hair and about nine months for the full effect.^[10] The pill is not suitable for everyone, so share the teen’s full medical and family history with the doctor.^[7]

Spironolactone

Evidence: Strong Spironolactone blocks some of the effects of androgens and can slow hair growth. It must never be taken during pregnancy, because it can harm the development of a male baby, so it needs reliable contraception.^[7][10] In adults, guidelines suggest adding an anti-androgen if hair growth is still a problem after six months on the pill.^[10]

Hair removal

Bleaching, waxing, shaving, depilatory creams, electrolysis and laser are all options for teens. Some people react to depilatory creams, so patch-test first. Eflornithine cream (Vaniqa) can slow facial hair regrowth but must be used every day.^[7] For age-appropriate tips, see shaving your face as a woman and should I shave my stomach as a girl?

Healthy habits

Evidence: Limited For teens with overweight, weight loss can reduce insulin resistance and improve PMOS symptoms. The Pediatric Endocrine Society suggests at least 150 minutes of activity a week, avoiding sweet drinks and limiting refined carbohydrates.^[7] Lifestyle changes help metabolic health, but their direct effect on hair is modest.^[10]

Talking with your child about it

Unwanted hair can be hard for a child or teen, and early puberty can cause anxiety about being different.^[3] Keep conversations calm, use plain words and avoid making hair sound like something shameful. Our article on what women with hirsutism want you to know may help you understand how it feels.

When to see a doctor

See a pediatrician if your child has:

• Pubic or underarm hair, body odor or acne before age 8 in a girl or 9 in a boy^[2]
• Breast development before age 8^[3][5]
• Very fast growth, or hair growth that gets worse quickly^[2]
• Signs of virilization, such as a deepening voice or an enlarged clitoris. See what is virilization?
• In teens: heavy facial or body hair together with irregular or missing periods^[7]

For teens, our hirsutism self-check can help put hair growth into context before the appointment.

Frequently asked questions

Is it normal for a baby to have hair on their back?

Yes, fine body hair is common in newborns, especially those born early, because lanugo is normally shed late in pregnancy.^[1] Thick, dark hair or hair that keeps increasing should be checked.

Why does my 6-year-old have pubic hair?

A common reason is premature adrenarche, which is usually harmless, but it should be checked by a doctor to rule out other causes.^[2]

Can a child have PCOS?

PMOS (formerly PCOS) is diagnosed in teens, not young children, and diagnosis in early adolescence is tricky because periods are often irregular at first.^[7][8]

Is facial hair normal during puberty?

Some extra hair is normal as androgen levels rise. Heavy hair growth with irregular periods is worth checking.^[7]

Key takeaways

• Fine body hair in babies is usually normal lanugo or vellus hair.
• Early pubic or underarm hair is often premature adrenarche, but always needs a doctor’s check.
• Precocious puberty means signs of puberty before age 8 in girls or 9 in boys.
• In teens, PMOS (formerly PCOS) is a common cause of hirsutism, but diagnosis is tricky in the first years after periods start.
• The combined pill can be considered for teens, and anti-androgens always need reliable contraception.

Sources

1. DermNet. Hypertrichosis. Accessed October 2026. Link
2. Pediatric Endocrine Society. Premature adrenarche. Accessed October 2026. Link
3. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). About puberty and precocious puberty. Accessed October 2026. Link
4. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). What causes normal puberty, precocious puberty, and delayed puberty?. Accessed October 2026. Link
5. Pediatric Endocrine Society. Precocious puberty: a guide for families. Accessed October 2026. Link
6. MedlinePlus Genetics. 21-hydroxylase deficiency. Accessed October 2026. Link
7. Pediatric Endocrine Society. Polycystic ovary syndrome. Accessed October 2026. Link
8. Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2023;108(10):2447-2469. PubMed 37580314
9. Teede HJ, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. Lancet. 2026;407(10545):2329-2339. Published online May 12, 2026. PubMed 42119588
10. Martin KA, Anderson RR, Chang RJ, et al. Evaluation and Treatment of Hirsutism in Premenopausal Women: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(4):1233-1257. PubMed 29522147

This article is for education and is not medical advice. Talk to a doctor about diagnosis and treatment.