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What Happens When Boys Reach Puberty?

In the space of a few years the human body develops and matures from childhood to adulthood; this is called ‘puberty’.

Boys’ and girls’ bodies are quite similar while they are children, although they have different sex organs. During puberty boys and girls become more different. Boys often enter puberty when they are around eleven to thirteen years old, and it is usually finished by the time they are sixteen to seventeen years old.

Puberty starts when the brain releases hormones that cause the testicles to produce the male sex hormone ‘testosterone’. This hormone affects many different parts of the body. 

The first thing that happens during puberty is that the testicles grow larger, and after that the penis also increases in size.

The testicles also start to produce semen, so that sexual intercourse can lead to pregnancy. It is common for boys to have their first ejaculation of semen at twelve to fourteen years old, this usually happens while they sleep at night. When boys reach puberty it is common that they get an erection (the penis becomes stiff) more frequently than before. It’s quite normal they get an erection several times during the night and many waken up with an erection in the morning.

Before puberty the foreskin can’t normally be pulled back over the head of the penis, but during puberty the foreskin enlarges and in most cases it can be drawn back without discomfort when puberty is over.

At the same time as the penis starts to grow, hair starts to grow around the scrotum and the penis. Hair also grows in the armpits, and later on hair will also grow on the inside of the thighs, around the anus and many men also get hair on their chest and stomachs. Towards the end of puberty boys start to grow a beard and beard growth increases for several years after puberty.

During puberty the body grows more quickly than previously. Testosterone also makes the vocal cords and larynx grow so that the voice becomes deeper. The skeleton gets stronger and the shoulders grow broader. Testosterone also makes the muscles grow. When puberty is over, boys have on average a 50 per cent heavier skeleton and 50 per cent more muscle mass than girls. It’s quite normal to put on weight and eat more food when you enter puberty.

Hormone changes also make boys sweat more than before, and the sweat has a more ‘adult’ odour. The skin produces more fats that can also lead to spots. Some boys experience mood swings more than they did previously, but these stop gradually over time.

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