Healthy body

Stages of puberty: what happens to boys and girls

Puberty is when a child's body begins to develop and change as they become an adult.

Girls develop breasts and start their periods. Boys develop a deeper voice and facial hair will start to appear.

The average age for girls to begin puberty is 11, while for boys the average age is 12.

But it's different for everyone, so don't worry if your child reaches puberty before or after their friends.

It's completely normal for puberty to begin at any point from the ages of 8 to 14. The process can take up to 4 years.

Late or early puberty

Children who begin puberty either very early (before the age of 8) or very late (after 14) should see a doctor just to make sure they're in good health.

Read more about puberty problems.

First signs of puberty in girls

The first sign of puberty in girls is usually that their breasts begin to develop.

It's normal for breast buds to sometimes be very tender or for one breast to start to develop several months before the other one.

Pubic hair also starts to grow, and some girls may notice more hair on their legs and arms.

Later signs of puberty in girls

After a year or so of puberty beginning, and for the next couple of years:

  • girls' breasts continue to grow and become fuller
  • around 2 years after beginning puberty, girls usually have their first period
  • pubic hair becomes coarser and curlier
  • underarm hair begins to grow – some girls also have hair in other parts of their body, such as their top lip, and this is completely normal
  • girls start to sweat more
  • girls often get acne – a skin condition that shows up as different types of spots, including whiteheads, blackheads and pus-filled spots called pustules
  • girls have a white vaginal discharge
  • girls go through a growth spurt – from the time their periods start, girls grow 5 to 7.5cm (2 to 3 inches) annually over the next year or two, then reach their adult height
  • most girls gain weight (which is normal) as their body shape changes – girls develop more body fat along their upper arms, thighs and upper back; their hips grow rounder and their waist gets narrower

After about 4 years of puberty in girls

  • breasts becomes adult-like
  • pubic hair has spread to the inner thigh
  • genitals should now be fully developed
  • girls stop growing taller

First signs of puberty in boys

  • the first sign of puberty in boys is usually that their testicles get bigger and the scrotum begins to thin and redden
  • pubic hair also starts to appear at the base of the penis

Later signs of puberty in boys

After a year or so of puberty starting, and for the next couple of years:

  • the penis and testicles grow and the scrotum gradually becomes darker (read more about penis health)
  • pubic hair becomes thicker and curlier
  • underarm hair starts to grow
  • boys start to sweat more
  • breasts can swell slightly temporarily – this is normal and not the same as "man-boobs"
  • boys may have "wet dreams" (involuntary ejaculations of semen as they sleep) 
  • their voice "breaks" and gets permanently deeper – for a while, a boy might find his voice goes very deep one minute and very high the next
  • boys often develop acne – a skin condition that shows up as different types of spots, including whiteheads, blackheads and pus-filled spots called pustules 
  • boys go through a growth spurt and become taller by an average of 7 to 8cms, or around 3 inches a year, and more muscular

After about 4 years of puberty in boys

  • genitals look like an adult's and pubic hair has spread to the inner thighs
  • facial hair begins to grow and boys may start shaving
  • boys get taller at a slower rate and stop growing completely at around 16 years of age (but may continue to get more muscular) 
  • most boys will have reached full adult maturity by the age of 18

Mood changes in puberty

Puberty can be a difficult time for children. They're coping with changes in their body, and possibly acne or body odour as well, at a time when they feel self-conscious.

Puberty can also be an exciting time, as children develop new emotions and feelings.

But the "emotional rollercoaster" they're on can have psychological and emotional effects, such as:

Find out more about teen aggression, coping with your teenager and talking to your teen.

Puberty support for children

If children are worried or confused about any part of puberty, it may help them to talk to a close friend or relative.

Puberty support for parents and carers

  • The Royal College of Psychiatrists website gives advice for parents and carers on what to expect when children hit adolescence, including why they're likely to become sulky, suddenly start dieting, have crushes on friends, and crave excitement.
  • The FPA (formerly the Family Planning Association) has a range of online leaflets that give advice on talking to your children about growing up, sex and relationships.

Page last reviewed: Fri Nov 2018 Next review due: Tue Nov 2021

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