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Puberty information for boys and girls


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As you start to become an adult, your body goes through lots of changes and you’ll notice that your moods and behaviour change too. From starting your periods to growing body hair, find out what to expect when you go through puberty.

What is puberty?

It’s when your body starts to develop and change, showing that you are starting to become an adult. These changes are very normal, and you may start to have sexual feelings and notice your moods and emotions changing, too.

When does puberty happen?

There is no set age for puberty so try not to worry if your body changes earlier or later than your friends’. For girls, puberty often happens between 10 and 16,1 and for boys between 10 and 18.2

Remember that changes will happen over time. Everyone’s body is different so some people develop very quickly and others more slowly.

Puberty in girls – changes to the body

Sex organs

One of the main physical changes of puberty is the growth and development of the sex organs – used to have sex and make babies.

During puberty your vagina changes and starts to produce a clear or milky liquid called discharge. It may seem strange at first but it’s a positive sign as it helps to keep your vagina healthy.

Female stages of puberty


Your nipples and breasts will start to fill out during puberty. However, breasts grow into a variety of shapes and sizes, and many women’s breasts remain small.

"All my friends wear bras every day but I don't know if I am ready to wear a bra yet. My mum says 'Your breasts are developing', but they are really small! I only have two bras so far, and when I wear them I feel like my breasts are fake because they are padded ones. I hope soon that I will feel self-confident about who I am." - Elin

It’s normal for one breast to grow faster than the other. Usually breasts become more even as they reach full development, but most breasts will always be slightly uneven in shape and size.

Female stages of puberty - breast development


One of the biggest changes for girls is periods starting. Again, this happens at different times for different people. While the average age for periods to start is 12,3 many girls experience them earlier and lots don’t get them until later.

Periods show that your body can now have a baby. Each month one of your ovaries releases an egg which can be fertilised by a boys’ sperm to create a pregnancy. If the egg isn’t fertilised, the lining of the womb breaks down, creating the blood that passes through your vagina during your period.4

Other changes for girls

  • Hair grows under your arms and between your legs. Your leg hair may get thicker and darker and you may grow hair on your upper lip.
  • Many girls start to get spots.
  • It’s normal to experience more body sweat and many girls start to use deodorant.
  • Rapid growth spurts.

Puberty in boys - changes to the body

Sex organs

As a boy goes through puberty his penis grows bigger and longer, and his testicles move lower down his scrotum. Sometimes one testicle grows faster than the other, and it is natural for one to hang lower than the other.

It’s usual to get more erections at odd times, often when you aren’t thinking about sex. You might also have 'wet dreams' - when you ejaculate in your sleep.

Male stages of puberty

Other changes for boys:

  • Pubic hair starts to grow at the base of your penis and under armpits.
  • Growing facial hair.
  • Your voice starts to get deeper, also known as ‘breaking’. For some boys this happens quickly and for others it takes time.
  • It’s normal to experience more body sweat and many boys start to use deodorant.
  • Many boys start to get spots.
  • Rapid growth spurts.

If you don’t fit ‘girl’ or ‘boy’

Not everyone fits simply into the category ‘girl’ or ‘boy’. There is help out there for those who think they may be ‘transgender’ - where they have a girl’s body but feel like a boy, or the other way around. If you have experienced this, you may find the information on the Advocates for Youth site useful.

New feelings and emotions

It’s perfectly normal to start thinking about sex a lot more during puberty, and most people start to explore and touch their bodies too. This is called masturbation. It may seem strange when you start doing this, but masturbation is a very natural way to make you feel good and is nothing to be ashamed of.

Some people find that they start becoming attracted to people of the same sex, the opposite sex, or both during puberty. Others may not be attracted to anyone. This is perfectly normal, and you shouldn't feel worried about it. Some people discover their sexuality when they are very young, during puberty or when they are much older – this is fine too.5

It can be exciting to start developing new emotions and feelings, but it may sometimes bring sad thoughts and feelings too.

If you’re experiencing mood swings or feeling aggressive or depressed it often helps to talk to someone you trust, such as a friend or relative. If you feel you need more support it may also help to contact a healthcare professional or a helpline.

Photo credit: © Debenport. Photos are used for illustrative purposes. They do not imply any health status or behaviour on the part of the people in the photo.

Photo credit: © Luzzatti Buyé
Photo credit: © Luzzatti Buyé
Last full review: 
01 May 2015
Next full review: 
01 May 2018

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Last updated:
09 May 2017
Last full review:
01 May 2015
Next full review:
01 May 2018