Kids' Health
Visit website  
Home › Topics › Nearly Teens > 

Puberty - boy changes, girl changes

puberty; boy; girl; physical; changes; change; grow; pimple; hair; periods; wet; dream; voice; menstruation; weight; breasts; muscles; penis; testes; erection; semen; body; shape; hormones; pad; testicles; growth; spurt; genes; pubic; periods; period;


    As you begin to go through puberty you grow taller, stronger, heavier, hairier, smellier, moodier and you may get pimples! Other changes depend on whether you are a girl or a boy.

Girls' changes

  • female bodyBodies become curvier and hip bones widen.
  • There is weight gain, particularly on the hips. This does not mean you have to start a diet to lose weight. In fact you would be unhealthy if you did not put on some weight. It just means that you are getting a womanly shape. Just continue to eat healthy foods and get regular exercise.
  • Muscles get bigger and stronger, but they do not show up as much as boys' muscles.
  • Breasts start to develop. First there is a small swelling under the nipples, and then the whole breast area starts to get bigger.
  • Menstruation (say men-stroo-ay-shun) (periods) starts.
  • You may get some whitish jelly from your vagina before or in between periods. (Don't worry it's just your body's way of cleaning itself.)

Boys' changes

male body
  • Boys gain weight.
  • Shoulders get wider.
  • Muscles start to get bigger and stronger.
  • You may notice that you are geting an 'Adam's apple'. This is your larynx or voice box getting larger and sticking out at the front of your throat. Your voice may seem to be all over the place, squeaky then deep or even sound like it is cracking. Don't worry - when your larynx has finished growing your voice will sound 'normal' again and probably a bit deeper than before.
  • Penis gets longer and wider.
  • Testes (or testicles) get larger.
  • Breasts look like they're developing a bit! (Don't worry this is quite normal and usually goes away by the end of puberty. See our topic Boys' breasts for more information.)
  • Apart from hair starting to grow on your body, it also grows on your face, like a beard, moustache or sideburns.   Usually it's pretty thin at first but gets stronger and darker towards the end of puberty.
  • You get erections sometimes because you're nervous or excited and other times when it just happens by itself! This can be a bit embarrassing at first but other people don't usually notice them as much as you do and if you don't think about the erection or you concentrate on something really boring (like saying the alphabet backwards) things will settle down again.

You may have 'nocturnal emissions' or wet dreams while you are sleeping. The 'wet' stuff is semen and you haven't wet the bed! It is also a normal part of growing up. (See our topics Sexual reproduction and Secret boy's business for more information.)

Both have to deal with

  • pubertyChanging body shape.
  • People responding to you differently. If you are tall for your age, people may think you should 'act older,' or if you are small for your age they may insist on treating you like a little kid. Some people may talk to you in an embarrassing way (see our topic Sexual feelings) or touch you when you don't want to be touched. Let them know that you don't like this by saying politely but firmly "I don't like it when you talk/touch me like that." Our topic 'Keeping yourself safe from child abuse' has more about this. 
  • Mixed up feelings and mood changes. This is a hormonal thing and is very difficult for kids and their parents to deal with (see our topic Family relationships)
  • One minute you have lots of energy and the next you feel so absolutely dead tired that you just want to be left alone to 'veg out'. This is particularly difficult for parents to understand - especially when the tiredness only seems to happen when it's time to do your chores or homework! (OK, OK, I'm just kidding!)
  • Changes in the way you think. See our topic 'Puberty - changes in thinking'. It's a good idea for parents to check this topic out too, especially when they say things like, "What were you thinking?"

pubertySeriously though, this is a time that is exciting and a bit scary so:
Don't be afraid to ask questions.

Take some time to get to know yourself.

Look after yourself by eating healthily, exercising (it makes you feel good) and getting plenty of rest so that your body has the energy to cope with all the growing it has to do.

Answering your questions


  • How will I know when it is time for my first period?
    • First ask mum when she had her first period as this will give you a good idea. (Your genes have a lot to do with how and when your body grows and develops.)
    • As a rough guide, you usually start your periods 12-18 months after your breasts start to develop.
    • Have a look at the topic Periods - facts and questions.
  • pubertyWhat if I start when I'm not at home?
    • Don't worry, you will not start with a great 'flood', so you will have time to ask a teacher, school service officer or ask to ring your mum if you are at school. Start carrying a 'pad' in your bag or leave one in your locker just in case.
    • Remember all females menstruate (have periods), so any female will know how to help you.
  • When does Puberty stop?
    • It usually takes a few years for all the changes to take place. A person's body is fully adult a couple of years after reaching their adult height.

(Adult height is usually reached by the age of 17 for girls and 19 for boys.)


  • Why am I so much bigger than, or smaller than, other kids in my class?
    • Not everyone grows at the same time or the same rate. Some people have their growth spurt really early and others really late. Kids who are really tall in year 7 are mostly about the same as everyone else in year 10.
    • If you are really concerned, ask mum and dad when they did their growth spurt. (It's those genes again!)
  • What happens when your voice 'breaks'?
    • pubertyYou can see how fast you are growing on the outside but you can't see that inside your body is growing too. As a boy reaches puberty the larynx (voice box) grows, which causes the pitch of the voice to change. The pitch gets lower and the voice sounds less like a child. Sometimes the sound seems to 'break' part way through speaking so that you may sound a bit like you're yodelling!
    • It will settle down.
    • Some men are able to sing in the high voice they had as a child as well as their deeper adult voice. This is called singing 'falsetto'. The voice sort of 'changes gear' to get into the high range.

Dr Kim says

Dr Kim
"Do you know the story of the ugly duckling that turned into a swan?

There may be times during puberty when you feel that you have a lot in common with the duckling! Gradually though, you will turn into a swan! Well perhaps not, but you will turn into the wonderful, unique adult that is you."

back to top

We've provided this information to help you to understand important things about staying healthy and happy. However, if you feel sick or unhappy, it is important to tell your mum or dad, a teacher or another grown-up.


Home › Topics › Nearly Teens >