Early Puberty in Boys

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Puberty is the time when boys’ bodies and minds mature and they grow into young men. This usually starts when a boy is about 12 years old. Sometimes, though, a much younger boy starts to show the signs of puberty. This is called precocious (pre-KOH-shuss), or early puberty (PU-ber-ty). These early signs of puberty can be hard for your child. 

Precocious Puberty in Boys

In boys, some of the signs of precocious puberty are:

  • Growth of the testicles
  • Growth of the penis
  • Growth of pubic, underarm or facial hair
  • Rapid height growth - a growth "spurt"
  • Voice deepening
  • Acne
  • “Adult” body odor   

Talk to your doctor if your son is less than 9 years of age and he shows any of these signs.

Causes of Precocious Puberty

where the pituitary gland is located in the brainThe start of puberty is caused by the hypothalamus (the part of the brain that controls the pituitary gland). It tells the pituitary gland (a pea-sized gland near the base of the brain) to release hormones (Picture 1). These hormones stimulate a boy’s testicles to make sex hormones.

Sometimes a problem in the brain, such as injury, a tumor or an infection causes early puberty. A problem in the thyroid gland could also start puberty early.

Some boys can have “partial” precocious puberty and may have growth of pubic or underarm hair but no other sexual development. Children with "partial" early puberty may need to be seen by a doctor.

How it Affects the Child

When puberty is finished, a boy will stop growing. Children with untreated early puberty sometimes do not reach their full adult height, because their bones mature and bone growth stops too soon. Even though they may have an early growth spurt that makes them taller than other children their age, finishing puberty early makes them stop growing too soon.

Early puberty can be hard for your child to deal with emotionally and socially. Boys may be more aggressive and develop a sex drive that does not match their age. The hardest part may be the teasing these children sometimes face from others.


Your child's doctor may order blood tests to check hormone levels. X-rays of your child's hand may be done to see if the bones are growing too fast. Other tests to help rule out specific causes may include: CT scans (see Helping Hand, CT ScanHH-III-199), MRIs (see Helping Hand, MRI (Magnetic Resonance Imaging), HH-III-69), and ultrasounds (see Helping Hand, Ultrasound scan, HH-III-64).


Children with precocious puberty can be treated. Doctors can help your child to grow to reach his full adult height and help stop the emotional and social problems he may face from maturing early.

If his doctor thinks your son has precocious puberty, he may be sent to a pediatric endocrinologist (a doctor who specializes in growth and hormonal disorders in children).

Depending upon the cause, treatment may include:

  • Treating the underlying cause or disease.
  • Using medicines to lower the levels of hormones and delay sexual development.

Sometimes no treatment is needed. 

Caring for Your Child

Give your child a simple, truthful explanation about what's happening. Explain these changes are normal for older children and teens, but that his body has started developing a little too early. Try not to focus on your child's appearance. Instead, offer praise for achievements in school, sports and other activities. Watch for signs that teasing or other problems may be affecting your child. Warning signs to watch for and talk to his doctor about include:

  • Poor grades, problems at school
  • Loss of interest in daily activities
  • Depression

Precocious (Early) Puberty in Boys (PDF) 

HH-I-288 9/11 Revised 3/17 Copyright 2011, Nationwide Children’s Hospital