Puberty: Normal Growth and Development in Boys

Your child has reached the stage of adolescence called puberty. During this stage, your child’s body begins to develop and gain sexual maturity. This sheet tells you what to expect during this stage of your child’s growth and development.

How long does puberty last?

In boys, puberty usually begins between the ages of 10 and 16. Once it begins, it lasts about 2 to 5 years. But every child is different. And there is a wide range of what is “normal.” Your boy may begin puberty a little earlier or later and finish sooner or later than his friends. If you have questions or concerns about your child’s development, talk to your child’s healthcare provider.

Physical changes during puberty

• Height and weight changes:

  • About 20% of total adult height is gained during puberty. Typically, boys have their height spurt fairly late in puberty.

  • About 50% of normal adult weight is gained during puberty. Boys often have a lower percentage of body fat by the end of puberty.

• Voice changes: Boys' voices get lower and deeper during puberty.

• Sexual changes and hair growth:

  • At the start of puberty, the testicles increase in size, drop lower, and the scrotum darkens, becomes looser, and becomes dotted with small bumps. Later in puberty, the penis begins to grow and mature.

  • Pubic hair begins to grow shortly after changes in the scrotum. At first it may be thin. It then gets darker and coarser. Boys also begin to grow hair in other new places, such as the chest, underarms, face, and legs about 2 years after the start of pubic hair growth. 

  • Erections (stiffening of the penis as it becomes filled with blood) and nocturnal emissions (“wet dreams”) happen. This is most common in the later stages of puberty as the body begins to make sperm.

• Acne and body odor:

  • Hormones that increase during puberty can cause acne on the face and body.

  • Hormones also increase sweating and cause a stronger body odor.

Reassuring your child

• Your child may be concerned that his peers are more or less developed than he is. Explain to your child that kids of the same age may be at different stages of puberty. Your child’s growth, whether slow or fast, is happening at the right rate for him.

• Help your child adjust to his changing body. Offer solutions for body odor and acne (such as bathing more often, using deodorant, and using acne products).

• Your child will likely feel uncomfortable discussing sexual changes with you. Let him know you are there to talk to. You may also consider giving your child a book with information about puberty that he can read on his own.