Growing Up: The Stages of Puberty for Boys

Timing will vary, but stages of development shouldn't
teen boy looking out window pensive

A cracking voice. Wild growth spurts. A little facial hair sprouting on the chin. Welcome to puberty for boys, a rite of passage that bridges the gap between childhood and manhood.

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The stages of male puberty follow a definite path with a progression of physical changes. The timing of these changes, however, varies widely from person to person.

Let’s look at the process with adolescent medicine specialist Veronica Issac, MD.

When do boys hit puberty?

Boys tend to begin and end puberty sometime between age 10 and 18. (That’s about two years later than girls.) Black and Hispanic children tend to enter puberty a bit earlier than white children.

A tool called the Tanner Stages outlines the stages of puberty for boys (and girls), and when they’re likely to occur. For parents, they can serve as an excellent guide to the changes you can expect to see.

Here are the five stages of puberty for boys and the signs of each.

Stage 1: Boyhood

In this “prepubescent” stage, boys have not experienced visible changes. Their brain, however, is starting to send signals about what’s ahead.

Stage 2: Physical changes begin

In this stage, typically beginning between age 9½ and 14½, boys experience:

  • Genital development (growth of the testicles and scrotum).
  • The growth of sparse hair around the penis and under their arms.
  • An increase in height (typically about 2 to 2½ inches per year), which could bring growing pains.

Stage 3: Physical changes accelerate

In this stage, occurring between age 10 and 16½, boys experience:

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  • Continued growth of the penis and testicles, as well as possible “wet dreams,” or ejaculation at night while they sleep.
  • Darkening, coarsening and more coverage by hair of the genital area.
  • Continued increase in height (about 2¾ to just over 3 inches) per year.
  • More sweating, which can lead to body odor.
  • Vocal changes (and cracking in the process).
  • Increased muscle mass.

“Some breast development, or gynecomastia, may occur in about 50% of all teenage boys, but it typically resolves by the end of puberty,” notes Dr. Issac. “If this becomes an issue physically or socially, suggest that your son talks with his healthcare provider.”

Stage 4: Puberty hits full stride

In this stage, which can occur between ages 11 and 16½, boys experience:

  • Growth in penis size and darkening of the skin on the scrotum and testicles.
  • Body hair growth that reaches adult levels.
  • A peak growth spurt that averages nearly 4 inches per year.
  • Development of acne.
  • Continued cracking of the voice. 

Stage 5: The final phase

Boys finish their growth and physical development during this stage. Many may not develop facial hair until this step in the process. Most boys finish growing by age 17.

Don’t hesitate to talk to your pediatrician when you have concerns about your son’s progress through puberty, says Dr. Issac. A physical exam and other tests will help to rule out problems, pinpoint underlying issues or provide you with reassurance. 

The emotional side of puberty

Whenever your son enters puberty, you can expect to see some emotional upheaval. Increased testosterone coupled with social pressures may cause moody behavior, emotional outbursts and family discord.

Parents can typically ride out these issues. (Read what a pediatric psychologist says about talking to your teen.)

“However, if serious emotional problems arise — if your son doesn’t want to do the things he usually enjoys, or hang out with his friends or experiences a drop in grades — it’s important to have him evaluated with his pediatrician,” says Dr. Issac.

Emotional issues could be a sign of a mood disorder or other psychological concerns, notes Dr. Issac. Medication and/or therapy may be useful in these instances.

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What if puberty hits really early or late?

Not everyone is on the same timetable. Some boys begin to see changes very early, which is called precocious puberty. Others may not see changes until later, which is often referred to as delayed puberty.

Let’s look at each situation.

Precocious (early) puberty

If your son shows signs of puberty before turning 9, visit the pediatrician. This may signal a pituitary problem or neurological issue, notes Dr. Issac. The doctor should evaluate your son as soon as you suspect a problem. 

Possible causes for early puberty include:

  • The pituitary gland “turning on” hormones too early.
  • Hypothyroidism (an underactive thyroid gland).
  • A tumor on the adrenal gland or elsewhere.

If the problem is hormonal, an endocrinologist can prescribe medication to halt puberty until the time is right. If your doctor suspects another problem, your son may be referred for further testing.

Delayed puberty

If your son starts puberty after age 14 or isn’t progressing through puberty, you’ll also want to check with your doctor. “Often the child is merely a late bloomer — particularly if dad was as well,” says Dr. Issac.

But hormone or endocrine abnormalities can also delay puberty. If your doctor suspects an underlying problem, your son will likely be referred to a specialist for more testing.

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