When?

There’s no “right” time for puberty to begin. But girls start a little earlier than boys, usually between 8 and 13 years of age. Puberty for boys usually starts at about 10 to 14 years of age.

What’s happening?

Chemicals called hormones will cause many changes in your body.

Girls only

Breasts. The first sign of puberty in most girls is breast development (small, tender lumps under one or both nipples). The soreness is temporary and goes away as your breasts grow. Don’t worry if one breast grows a little faster than the other. By the time your breasts are fully developed, they usually end up being the same size.

When your breasts get larger, you may want to start wearing a bra. Some girls are excited about this. Other girls may feel embarrassed, especially if they are the first of their friends to need a bra. Talk with your mom or another trusted adult about buying your first bra.

Curves. As you go through puberty, you’ll get taller, your hips will get wider, and your waist will get smaller. Your body also begins to build up fat in your belly, bottom, and legs. This is normal and gives your body the curvier shape of a woman.

Periods. Your menstrual cycle, or “period,” starts during puberty. Most girls get their periods 2 to 2½ years after their breasts start to grow (between 10 and 16 years of age).

During puberty, your ovaries begin to release eggs. If an egg connects with sperm from a man’s penis (fertilization), it will grow inside your uterus and develop into a baby. To help your body prepare for this, a thick layer of tissue and blood cells builds up in your uterus. If the egg doesn’t connect with a sperm, the body does not need these tissues and cells. They turn into a blood-like fluid and flow out of your vagina. Your period is the monthly discharge of this fluid out of the body.

A girl who has started having periods is able to get pregnant, even if she doesn’t have a period every month.

You will need to wear some kind of sanitary pad or tampon, or both, to absorb this fluid and keep it from getting on your clothes. Most periods last from 3 to 7 days. Having your period does not mean you have to avoid any of your normal activities, like swimming, horseback riding, or gym class. Exercise can even help get rid of cramps and other discomforts you may feel during your period.

Boys only

Muscles. As you go through puberty, you’ll get taller, your shoulders will get broader, and, as your muscles get bigger, your weight will increase.

Does size matter? During puberty, the penis and testes get larger. There’s also an increase in sex hormones. You may notice you get erections (when the penis gets stiff and hard) more often than before. This is normal. Even though you may feel embarrassed, try to remember that unless you draw attention to it, most people won’t notice your erection. Also, remember that the size of your penis has nothing to do with manliness or sexual functioning.

Wet dreams. During puberty, your testes begin to produce sperm. This means that during an erection, you may also ejaculate. This is when semen (made up of sperm and other fluids) is released through the penis. This could happen while you are sleeping. You might wake up to find your sheets or pajamas are wet. This is called a nocturnal emission, or wet dream. This is normal and will stop as you get older.

Voice cracking. Your voice will get deeper, but it doesn’t happen all at once. It usually starts with your voice cracking. As you keep growing, the cracking will stop and your voice will stay at the lower range.

Breasts? You may have swelling under your nipples. If this happens to you, you may worry that you’re growing breasts. Don’t worry, you’re not. This swelling is very common and only temporary. But if you’re worried, talk with your doctor.

New feelings

In addition to all the physical changes you will go through during puberty, there are many emotional changes. For example, you may start to care more about what other people think about you because you want to be accepted and liked. Your relationships with others may begin to change. Some become more important and some less so. You’ll start to separate more from your parents and identify with others your age. You may begin to make decisions that could affect the rest of your life.

At times, you may not like the attention of your parents and other adults, but they, too, are trying to adjust to the changes you’re going through. Many teens feel their parents don’t understand them; this is a normal feeling. It’s usually best to let them know (politely) how you feel and then talk things out together.

Also, it’s normal to lose your temper more easily and to feel that nobody cares about you. Talk about your feelings with your parents, another trusted adult, or your doctor. You may be surprised at how much better you will feel.

Sex and sexuality

During this time, many teens also become more aware of their sexual feelings. A look, a touch, or just thinking about someone may make your heart beat faster and may produce a warm, tingling feeling all over. You may not be sure if you are attracted to boys, girls, or both. That’s OK and you shouldn’t feel worried about it.

You may ask yourself...

• When should I start dating?

• When is it OK to kiss?

• How far should I go sexually?

• When will I be ready to have sexual intercourse?

• Will having sex help my relationship?

• Do I have to have sex?

• If I am attracted to a same-sex friend, does that mean I am gay or lesbian?

• What is oral sex? Is oral sex really sex?

• Is it OK to masturbate (stimulate your genitals for sexual pleasure)? (Masturbation is normal and won’t harm you. Some boys and girls masturbate; some don’t.)

Remember, talking with your parents or doctor is a good way to get information and to help you think about how these changes affect you.

Decisions about sex

Deciding to become sexually active can be very confusing. On the one hand, you hear many warnings and dangers about having sex. On the other hand, movies, TV, magazines, and even the lyrics in songs all seem to be telling you that having sex is OK.

It’s normal for teens to be curious about sex, but deciding to have sex is a big step.

There’s nothing wrong if you decide to wait to have sex. Not everyone is having sex. Half of all teens in the United States have never had sex. Many teens believe waiting until they are ready to have sex is important. The right time is different for each teen.

If you decide to wait, stick with your decision. Plan ahead how you are going to say no so you are clearly understood. Stay away from situations that can lead to sex. If your boyfriend or girlfriend doesn’t support your decision to wait, he or she may not be the right person for you.

No one should be forced to have sex! If you are ever forced to have sex, it’s important to never blame yourself and to tell an adult you trust as soon as possible. Medical and counseling supports are available to help someone who has been forced to have sex.

If you decide to have sex, it’s important you know the facts about birth control, infections, and emotions. Sex increases your chances of becoming pregnant, becoming a teen parent, and getting a sexually transmitted infection (commonly known as an STI), and it may affect the way you feel about yourself or how others feel about you.

These are important decisions and are worth talking about with adults who care about you, including your doctor. 

Taking care of yourself

As you get older, you will need to make many decisions to ensure you stay healthy.

• Eating right, exercising, and getting enough rest are important during puberty because your body is going through many changes.

• It’s also important to feel good about yourself and the decisions you make.

• Whenever you have questions about your health or your feelings, don’t be afraid to share them with your parents and doctor.