Body

When does puberty start, and how do I talk to my child about it?

Written by the Kids by Molliora editorial team, based on the sources below. Last updated: 26 October 2026

Short answer

Puberty usually starts between the ages of 8 and 14 and takes about 4 to 6 years in total (NHS, 1177). It often starts a little earlier in girls than in boys, and the timing varies a lot between children. Talk about the changes early and often, before they happen, and contact a doctor if signs of puberty start before age 8 or have not started by 15 (NHS).

What	Usual timing	Source
Puberty starts, girls	8–13 years	UMO
Puberty starts, boys	9–14 years	UMO
First period	Most at 12–13 years (range 9–16), about 2 years after the breasts start to develop	KidsHealth, 1177
Whole of puberty	4–6 years	1177, UMO

What changes during puberty?

Hormones start the changes, and they come gradually (1177, KidsHealth):

A growth spurt, and the shape of the body changes.
Hair grows under the arms and around the genitals. Most children sweat more and get oilier skin, often with spots. Washing every day and using deodorant helps.
The voice changes, most clearly in boys, whose voices get deeper.
In girls, the breasts usually start to develop first. They can be tender, and one side may grow before the other. The first period usually comes about two years later and is often irregular at first.
In boys, the penis and testicles grow, and wet dreams (ejaculating during sleep) are common. Some boys get temporary breast swelling. It is harmless and usually goes away.
Moods can go up and down, and many children get irritated more easily (1177). Many also need more sleep (1177).

How do I talk to my child about puberty?

Start before the changes begin. Some girls start puberty at 8 and some boys at 9, so earlier than many parents think (KidsHealth).
Have many short talks, not one big one. Do not wait for questions: many children do not know that it is OK to ask.
Talk about periods before they start, so the first one does not come as a fright.
Tell both girls and boys about the changes in both sexes, and ask the school what its sex education covers, so you know what to add.
Be reassuring: everyone goes through these changes, but not at the same pace. Answer honestly, and if you do not know, find out together.
If talking feels hard, leave a good book out, or tell your child about UMO.se (the Swedish youth health website), the school nurse or a youth clinic (1177).

What if my child is early or late?

The timing varies a lot and often runs in families (1177, NHS). Starting earlier or later than friends is usually nothing to worry about, but being the first or the last can feel awkward, so give a little extra support (KidsHealth). Illness, feeling mentally unwell or very hard training can delay or pause puberty (UMO). If needed, a doctor can check for causes, and puberty can be delayed or started with medicine (NHS, 1177).

Try this week

Ask an open question while you are doing something together, such as "Has anyone in your class started talking about puberty?"
Put deodorant and, if relevant, period pads in the bathroom, so your child does not have to ask.
Ask the school what its sex education covers this year.

When to get help

Contact your doctor if signs of puberty start before age 8, or if puberty has not started by age 15 (NHS). In Sweden, 1177 advises contacting the child health centre (BVC), your health centre or the school health service if a girl shows no signs of puberty by 13 or a boy by 14. Also talk to a health professional if your child often seems sad, nervous, irritable or hopeless (AAP), or if strong feelings about their body or gender are causing distress, which can become stronger during puberty (1177). In Sweden, young people can contact a youth clinic (ungdomsmottagning), and children can call or chat with Bris on 116 111. In an emergency, call 112 or your local emergency number.