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Puberty
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Sexual Health Issues

Puberty

Puberty is the transformative life stage when a young person achieves sexual maturity, typically occurring between ages 8 and 14.

Overview

Puberty is the time in life when a boy or girl becomes sexually mature. It is a process that usually happens between ages 8 and 13 for girls and ages 9 and 14 for boys. It causes physical changes and affects boys and girls differently.

Changes in Girls

  • The first sign of puberty is usually breast development.
  • Then hair grows in the pubic area and armpits.
  • Menstruation (or a period) usually happens last.

Changes in Boys

  • Puberty usually begins with the testicles and penis getting bigger.
  • Then hair grows in the pubic area and armpits.
  • Muscles grow, the voice deepens, and facial hair develops as puberty continues.

Shared Experiences

Both boys and girls may get acne. They also usually have a growth spurt (a rapid increase in height) that lasts for about 2 or 3 years. This brings them closer to their adult height, which they reach after puberty.

Frequently Asked Questions

Yes. Known as physiological gynecomastia, temporary breast tissue swelling or tenderness affects up to half of adolescent boys. It is caused by transient hormonal fluctuations between testosterone and estrogen during mid-puberty. In the vast majority of cases, the swelling resolves on its own within six months to two years without medical treatment.
Puberty is considered precocious (abnormally early) if secondary sexual characteristics appear before age 8 in girls (such as breast budding) or before age 9 in boys (such as testicular enlargement). Conversely, puberty is considered delayed if a girl shows no breast development by age 13 or has not menstruated by age 15, or if a boy shows no testicular enlargement by age 14. Both situations warrant evaluation by a pediatrician or pediatric endocrinologist.
pubertal growth spurt typically lasts between 24 and 36 months, during which teens achieve about 20 percent of their final adult height. For girls, peak height velocity usually occurs early in puberty, slowing significantly after the onset of menstruation. For boys, the growth spurt happens later in puberty. Growth plates (epiphyses) generally fuse between ages 14 to 16 for females and 16 to 19 for males, after which vertical growth stops.
During the first one to two years following menarche, the hypothalamic-pituitary-ovarian axis is still maturing. Many cycles are anovulatory (occurring without egg release), which frequently causes irregular intervals, varying flow intensity, or skipped months. While irregularity is normal initially, severe pain, bleeding lasting longer than seven days, or intervals shorter than 21 days or longer than 45 days should be evaluated by a healthcare clinician.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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