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Puberty in boys

Puberty is when your body changes, when you develop from being a boy to a man. Learn what changes to expect so that you feel more prepared.

Expect Changes with Puberty

Know that you will go through a growth spurt.

You have not grown this much since you were a baby. Usually boys start their growth spurt about 2 years after puberty starts. When you are done going through puberty, you will be almost as tall as you will be when you are a grown up.

Maybe you are worried about how tall you are or how tall you will get. How tall you get depends a lot on how tall your mom and dad are. If they are tall, you are likely to be tall. If they are short, you will probably be short too.

You will also start building some muscle. Again, you may be worried that other boys seem to be getting bigger faster. But puberty happens for each boy on their own body schedule. You cannot rush it.

Eat well, sleep well, and stay physically active to help you grow well. Some boys want to lift weights to build muscles. You will not be able to build muscle until you are in puberty. Before puberty, lifting weights will tone your muscles, but you will not build muscles yet.

Expect Lots of Body Changes

Your body makes hormones to get puberty started. Here are some changes you will start seeing. You will:

  • See your testicles and penis get bigger.
  • Grow body hair. You may grow hair on your face around your upper lip, cheeks, and chin. You may see hair on your chest and in your armpits. You will also grow pubic hair in your private parts around your genitals. As the hair on your face grows thicker, talk to your parent about shaving.
  • Notice your voice getting deeper.
  • Sweat more. You may notice that your armpits smell now. Showering every day and using deodorant can help with this if it is a problem.
  • Get some pimples or acne. Hormones cause this during puberty. Keep your face clean and use non-oily face cream or sunscreen. Talk to your health care provider if you are having a lot of problems with pimples.
  • Maybe have gynecomastia. This is when your breasts get a little enlarged. This is from hormones during puberty. The gynecomastia should last about 6 months to 2 years. About one half of boys will have it.

You will also get erections more often. An erection is when your penis becomes bigger, hard, and stands out from your body. Erections can happen at any time. This is normal.

  • You can have an erection when you are sleeping. Your underwear or bed maybe wet in the morning. You had a "wet dream," or what is called a nocturnal emission. This is when semen comes out of your urethra, the same hole that you pee out of. Wet dreams happen because your testosterone level goes up during puberty. This is all preparing your body to be able to father a child someday.
  • Know that semen has sperm in it. Sperm is what fertilizes a woman's egg to make a baby.

Know When Puberty Happens

Most boys start puberty somewhere between the ages of 9 and 16 years. There is a wide age range when puberty starts. That is why some kids in 7th grade still look like young children and others look really grown up.

Girls usually start puberty earlier than boys. That is why so many girls are taller than boys in 7th and 8th grade. As adults, many men end up taller than women.

Accept changes in your body. Try to be comfortable with your body changing. If you are stressed about changes, talk to your parents or a provider that you trust.

When to Call the Doctor

Contact your provider if you are:

  • Having pain or a problem with your penis or testicles
  • Worried that you are not going into puberty

Alternative Names

Well child - puberty in boys; Development - puberty in boys


American Academy of Pediatrics, website. Concerns boys have about puberty. Updated January 8, 2015. Accessed December 9, 2022.

Garibaldi LR, Chemaitilly W. Physiology of puberty. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 577.

Styne DM. Physiology and disorders of puberty. In: Melmed S, Anchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 26.

Review Date 10/22/2022

Updated by: Charles I. Schwartz, MD, FAAP, Clinical Assistant Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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