Version July 2025
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What is puberty? —
Puberty is the word for the changes the body goes through during the preteen and teen years.
The biggest changes during puberty are that children's bodies:
●Grow taller – Children usually grow a lot in a short time. This is called a "growth spurt."
●Become more like adults' bodies – As a child's body changes to an adult's body, it becomes possible for a girl to get pregnant and for a boy to get someone pregnant.
What causes puberty? —
Puberty is caused by hormones in the body. These hormones come from the brain as well as organs called the ovaries (in females) and the testicles (in males) (figure 1 and figure 2). The ovaries make a hormone called "estrogen." The testicles make a hormone called "testosterone." Both of these cause many of the changes in the body.
When does puberty usually start? —
Puberty starts at different times in different children. Girls usually start puberty between ages 9 and 12. Boys usually start puberty between ages 10 and 13.
But it can be normal for children to start puberty before or after these ages. When puberty starts depends on different factors, including a child's genes, nutrition, and weight.
Talk to your child before puberty starts. Tell them what body changes to expect and that these changes are normal.
What changes happen in girls? —
The changes that happen during puberty in girls are:
●The breasts begin to develop. The child might feel a lump in the center of their breast, sometimes called a "breast bud." In many cases, this is the first sign of puberty. One breast might develop a lump before the other. This is normal. Over time, the breasts will grow bigger.
●Hair grows in the genital area (pubic hair), under the arms, and on the legs. In some girls, pubic hair is the first sign of puberty.
●Girls start to get their monthly periods. These usually start about 2 years after the breasts or pubic hair starts growing. But they might start sooner or later. When a girl first starts getting her period, she might not get one every month. It is normal for a period to skip a month, or come more often during the first 1 to 2 years after periods start. Some girls feel bloated or have mood changes right before they get their period.
●Girls can have white or clear vaginal discharge. This is the small amount of fluid that comes out of the vagina.
What changes happen in boys? —
The changes that happen during puberty in boys are:
●The testicles get bigger. This is usually the first change.
●The penis gets longer and wider.
●Hair grows in the genital area (pubic hair), on the face, and under the arms.
●The voice changes.
●Boys can ejaculate a small amount of sperm at night while they sleep. This is sometimes called a "wet dream."
●The breasts can get slightly bigger. This usually goes away over time.
What other changes can happen during puberty? —
Other changes that can happen are listed below. These things are all normal, but some can be bothersome or embarrassing for a child. They include:
●Pimples (acne) – To help prevent pimples, your child can wash their face twice a day with a gentle non-soap facial skin cleanser. You can also ask your child's doctor or nurse for advice on how to treat pimples.
●Sweating under the armpits, and body odor – Puberty is when most children start using an antiperspirant or deodorant.
●Eyesight changes – Some children start needing glasses during puberty.
●Mood changes or mood swings
How should I teach my child about safe sex? —
During puberty, many teens start having sexual feelings. This is normal, and you can help by talking openly about sex with your child.
It's especially important to talk about safe sex. Even though a teen's body might look grown up, their thoughts and feelings are not always grown up. Because of this, many teens do not use protection, like condoms, during sex. This can lead to pregnancy or sexually transmitted infections ("STIs").
Talk to your teen about:
●How to avoid pregnancy and STIs – The only sure way to prevent these things is not to have sex. If teens do have sex, they can lower their chance of pregnancy by using birth control. But most types of birth control do not protect against STIs. To lower the chance of getting an STI, teens should also use a condom correctly every time they have sex.
●Consent – It's also important to talk to your teen about appropriate sexual behavior. For example, explain what "consent" means. Consent means agreeing to do something with another person. This does not only mean sexual intercourse, but also kissing, touching, or any other sex acts. It is not OK to do any of these things without the other person's consent.
How else can I support my child? —
You can help your child by being open and honest with them:
●Help them understand what to expect during puberty, and remind them the changes they are going through are normal.
●Make it clear you will support your child if they have questions about their gender identity or sexual orientation. "Gender identity" means how a person feels inside, and whether they identify as a girl or boy, some combination of both, or neither. "Sexual orientation" means a person's physical or sexual attraction to other people. A person can be attracted to people of their own gender, people of another gender, both, or neither.
●If your child is struggling with their body changes during puberty, or if they seem anxious or depressed, talk with their doctor or nurse. If your child's gender identity does not match their birth-recorded sex, puberty can cause severe distress. Their doctor or nurse can help you figure out how best to support your child.
Patient education: Early puberty (The Basics)
Patient education: Late puberty (The Basics)
Patient education: Menstruation (The Basics)
Patient education: Acne (The Basics)
Patient education: Teen sexuality (The Basics)
Patient education: Choosing birth control (The Basics)
Patient education: Sexually transmitted infections (The Basics)
Patient education: Being transgender (The Basics)
Patient education: Acne (Beyond the Basics)
Patient education: Adolescent sexuality (Beyond the Basics)
