Johns Hopkins All Children's Hospital

Puberty For Boys

Helpful information for boys about the different physical and emotional changes that take place during puberty.

When your child is about 10-12 years old, he'll start to notice different changes happening to his body and emotions. This is all a part of puberty.

As a boy, some of the physical and emotional changes your child will start to notice include:

  • Body parts changing and growing. For boys, one of the first changes is both testicles getting bigger in size.  After that, they will notice their penis grows longer and wider.
  • They will start to grow taller and stronger as their muscles get bigger.
  • They will start to have hair growing in different parts of the body such as the face, chest, arm pits and on the outside of the penis.
  • Their voices will start to change and at first sound like it’s squeaky or cracks a lot, but over time, it will become deeper.
  • Their moods might change and they may start to feel different. Some days they will feel happy and have a lot of energy, and some days they may feel more tired and not so happy or even grumpy.
  • The way they think about themselves and other people might change.
  • Your child might start thinking more about his future and start to question things happening around him at home, school, in his community or even on the news.

Physical Changes

Testicles and Penis Change in Size

For boys, the genitals include two testicles and one penis. During puberty, changes in size and shape of the genitals usually start between ages 9-14. 

The testicles are protected by skin that is called the scrotum. The testicles are the parts of the body that make a hormone called testosterone. Testosterone is what causes many of the other puberty changes that boys have like hair growth, voice changes, and muscle growth. Boys will also start to notice that their penis gets wider and longer during puberty. 

Genitals, testosterone, and emotions all work together, and it’s normal for boys to start having sexual feelings toward other people during puberty. When these feelings happen, it can cause changes in how the penis feels. For example, the penis may become hard; this is called an erection. This is a normal change for boys that usually lasts a few minutes, but what matters most is how they deal with it if they are in school or in public around other people. They may need to excuse themselves or wait a few minutes for the erection to end.

Body Hair

As boys go through puberty, one of the changes that they'll notice is that they will start to grow hair in new places. Boys will grow new hair underneath their arm pits, on their legs, arms, chest, face, and around the outside of the penis and testicles. Sometimes, people like to shave this new hair using shaving cream and a razor. Remind your child that he should talk to a trusted adult before deciding to do this so that he can learn how to shave safely. 

The hair on your child's head may change as well and he might notice that his scalp feels oilier. This is because during puberty hormones start to change and this might cause his sweat glands to make more sweat and natural oils in certain parts of the body, including the scalp. This may mean that your child will need to wash his hair more often. Shampoo helps to remove the dirt and any oil that builds up during the day. Conditioner afterwards will help to keep hair moisturized. 

All boys are born with unique and different hair texture. Some boys have very soft hair and some boys have very coarse hair. Often times boys with coarse hair only need to wash it every 1-2 weeks.  



Sweating is good because it helps to regulate body temperature. During puberty, your child's body begins to produce smellier sweat. Why this change? Our bodies have two types of sweat glands: eccrine glands and apocrine glands. The eccrine glands have been working since we were born, but when puberty starts our apocrine glands begin working. This sweat causes a body odor because it reacts with the bacteria on the skin.

It is very important that your child showers daily and doesn't forget to wash under his arms and in his groin area. He should also start to wear deodorant or antiperspirant under his arms every day. He should reapply deodorant after physical activity or as needed throughout the day. It may be a good idea to keep extra deodorant in his locker or backpack to use after PE class. There are many different kinds of deodorants and choosing the right one depends on his body and preferences.  

Groin sweat

Since boys also have sweat glands in their groin area near the penis and testicles, this area can become hot and sweaty especially after exercise or physical activity. A skin infection that boys can get in the groin area is commonly known as “jock itch.” “Jock itch” causes itching, irritation and sometimes red bumps on the skin.

There are a few things boys can do to prevent this. They should always change sweaty underwear to clean underwear when possible, don’t share used towels with anyone else, and use soap and water to clean this area during their daily showers. “Jock itch” is easy to treat. Some medications are found at your local pharmacy and some may need to be prescribed by your child's doctor.


Remind your child to brush his teeth at least twice per day. As he gets busier with school, activities, and homework, this can be easy to forget, but brushing his teeth will keep them healthy and cavity-free. It also keeps the teeth whiter and the breath smelling fresh. Your child should brush his teeth for two minutes and start at his gums and work his way around all of the teeth.  

After brushing, your child should also floss his teeth at least once per day. Small pieces of food and bacteria can get stuck in between the teeth. Flossing is a really important way to keep from getting cavities, gum infections, and bad breath. 


Showering daily helps clean away any dirt and oil build-up from the day. Showering often will keep your child feeling and smelling fresh and also prevent body odor and some acne. 


Most boys grow taller in height during the stage of puberty known as the growth spurt. This usually happens during the later stages of puberty after other physical changes have started, such as changes in the size of the genitals, body hair growth and voice changes. Boys may notice that girls in their class are taller than them and this is because it is normal for girls to start their growth spurt earlier than boys. By the time boys reach high school, they are often times taller than most girls by the end of puberty. 

It is important for boys to know that everyone grows taller and builds muscle at different speeds so it is best not to compare themselves to their friends. How much or how fast a person grows depends on their sleep patterns, exercise habits, nutrition, and family genetics.

Emotional Changes

Mood Changes and Sleep

As boys go through puberty, they may begin to have more mood swings. One minute they may feel happy, and then the next minute, they may feel sad. This is normal and happens because of hormone changes during puberty. Boys should be aware of how these mood swings affect them and those around them. When they start to feel overwhelmed, they should try to find healthy and safe ways to cope and manage these feelings. They can try things like taking a walk outside, talking to a friend, doing an activity to express themselves, or exercising. Encourage your child to talk to a trusted adult like a parent, school counselor, or doctor. Most importantly, help him remember that he is not alone. 

Sleep plays an important part in our moods. When your child is tired, he may be cranky, irritated, more emotional, and less likely to think through his decisions. Therefore, it is very important for children to get enough sleep. As a pre-teen, your child should be getting at least 9-12 hours of sleep a night.  

Having good sleep habits is extremely important. Your child can try things like:  

  • Make sure he has a consistent bed time (even on the weekends). His body will get used to the routine, and it will get easier to fall asleep and to wake up. 
  • Don’t use electronics, like a cellphone, for at least one hour before bed time.  
  • Keep his room cool, dark, and quiet. 

More information for boys and girls

Learn more about other topics for boys and girls, including nutrition, exercise, sleep, dealing with acne, developing strong relationships with family and friends, social media safety, and more.

Learn more

Still have questions? Come see us.

Our pediatric and adolescent medicine teams have special training to meet the unique needs of children, pre-teens and teens. We're here to help guide you and answer any questions you might have.

The information here is not intended to be nor should be used as a substitute for medical evaluation or treatment by a health care professional. This publication is for information purposes only and the reader assumes all associated risks.

Content expert: Jasmine Reese, M.D., M.P.H.