Physical changes that occur during puberty are usually marked by distinct stages of development known as Tanner stages. These were named after the child development expert, James Mourilyan Tanner, who first identified them.
The Tanner stages give average dates of development, although there can be significant variation among children and teenagers. You should not worry if you reach a stage of puberty before or after your friends do.
Tanner stage one
Tanner stage one describes the changes that take place in your body before the onset of puberty. These are sometimes known as pre-pubertal changes.
- changes usually occur at 8-10 years of age, but may start when you are as young as 6 or 7
- you will grow taller by 5-6cm a year (2-2.4 inches)
- your nipples may swell slightly
- your ovaries will begin to grow
- changes usually occur at 9-11 years of age
- you will grow taller by 5-6cm a year (2-2.4 inches)
Tanner stage two
- usually occurs at around 11 years of age
- your areola (area of skin that surrounds the nipple) will begin to swell
- pubic hair will start to develop along the labia (lips of the entrance to the vagina)
- the clitoris (a sensitive pea-sized nodule of tissue above the entrance to the vagina) and the womb will become larger
- you will grow taller by 7-8cm a year (2.8-3.2 inches)
- usually begins at about 12 years of age
- your scrotum (the pouch containing the testes) will begin to thin and redden; your testicles will increase in size
- fine pubic hair will start to appear at the base of your penis
- your body fat usually decreases, while you continue to grow taller by 5-6cm a year (1.9-2.3 inches)
Tanner stage three
- usually occurs after the age of 12
- your areola will continue to swell and you may need to buy your first bra
- your pubic hair will become coarser and curlier and you will begin to grow underarm hair
- you may develop spots (acne) on your face and back
- you will grow taller by an average of 8cm a year (3.2 inches) – the highest growth rate
- usually occurs after the age of 13
- your penis will grow and lengthen, and your testicles will continue to grow
- your pubic hair will become thicker and curlier, spreading to the soft mound of skin above your genitals
- your breasts should swell slightly (this is perfectly normal and does not mean you will grow 'man-boobs')
- you may begin to experience 'wet dreams' – involuntary ejaculations of semen ('come') during your sleep
- your voice should 'break' (the pitch and tone of your voice may start to suddenly change for short periods of time)
- the size of your muscles will increase, and you will grow taller by 7-8cm a year (2.8-3.2 inches)
Tanner stage four
- usually occurs at the age of 13
- your breasts slowly develop into a more adult shape, with your nipple and areola swelling to produce a second mound that sits on top of the breast (the second mound will disappear once the rest of your breast develops)
- your pubic hair will start to look more adult-like in appearance, but will not spread to your inner thigh
- you will usually start your first period and should be having regular periods by the end of the stage
- your growth rate will begin to slow down, growing taller by an average of 7cm a year (2.8 inches)
- usually occurs at around 14 years of age
- your penis and testicles will continue to grow, and your scrotum will become darker
- your pubic hair will appear more adult-like, but will not have spread to your inner thighs
- you should start growing underarm hair
- your voice will change permanently
- you may develop acne
Tanner stage five (final stage)
- usually occurs at just over 14 years of age
- the swelling of your areola will disappear as the rest of your breast becomes adult-like in shape
- your pubic hair should spread to your inner thigh
- your genitals should have fully developed by the end of this stage
- by around 16 years of age you should stop growing and you will be physically mature
- usually starts at about 15 years of age
- your genitals will look like an adult’s, and pubic hair will spread to the inner thigh
- you will begin to grow facial hair and may have to start shaving
- your growth should slow down and you should stop growing at around 17 years of age (but your muscles may continue to grow)
- most boys will reach full adult maturity between 18 and 19 years of age
During puberty, your body becomes more sensitive to the hormone testosterone, which is present in both boys and girls. Testosterone causes small glands in your skin to produce too much oil (sebum).
Dead skin can also block the opening of hair follicles (the small tubes in your skin that hold a hair in place). The sebum can build up behind the blocked follicle, which can cause blackheads or whiteheads (spots) to develop.
Hormonal changes will also alter the levels of acid in your skin, encouraging the growth of bacteria. When bacteria infect a blocked hair follicle, they can produce a deeper infection, such as a spot (pustule) or nodule.
Mild to moderate acne can usually be treated using an antibacterial cream. If your acne is more severe, your GP may recommend antibiotic tablets.
Read more information about acne.
During puberty, your body begins to develop large sweat glands around your armpits, breasts and genitals. These are known as apocrine glands. Apocrine glands release sweat in response to stress, emotion and sexual excitement. In some cases, the excess sweat can cause body odour.
Read more information about body odour.
A girl's periods usually start between the age of 10 and 16; usually at 12-13. Your periods will continue until the menopause, which usually occurs at 45-55 years of age.
In the days leading up to your period, you may have a number of symptoms including:
- sore breasts
- feeling very emotional or upset
These symptoms should pass once your period starts. Many girls and women feel pain or cramping in their abdomen (tummy), back and vagina. This is often referred to as period pain. Taking paracetamol may help to relieve period pain.
Read more information about periods.
Psychological and behavioural changes
For many, puberty can be a particularly difficult time. You are forced to cope with changes in your body and possible side effects, such as acne or body odour, just at the time when you feel self-conscious about your body and self-image.
Puberty can also be an exciting time, as you develop new emotions and feelings. However, the 'emotional rollercoaster' experienced during puberty can have psychological and emotional effects, such as:
- unexplained mood swings
- low self-esteem
These feelings can be a normal part of growing up and going through puberty. But if they are having a serious impact on your life, you may wish to talk to someone close to you, such as a close friend or relative, or go to your GP for advice.