Periods

Key points

Periods are a normal part of puberty. They usually start between the ages of nine and 15, but every young person is different.
Periods usually happen once a month and last two to seven days.
It is common for periods to be irregular during the first three years.
Cramps, mood changes, and tiredness are common symptoms of periods.
If you are worried about your child’s pain or any other symptoms related to their period, speak with a doctor.

Read the teen fact sheet

What are periods?

A period, or menstruation, is when blood and tissue lining the uterus leave the body through the vagina. Periods usually start during puberty and happen once a month.

Most periods last between two and seven days, but there is a wide range of what is considered ‘normal.’ Some people may have a shorter period, while others may have a longer one. The amount of blood lost is different for everyone, but is usually between 20 and 90ml (millilitres).

When do periods usually start?

Most people get their first period between the ages of nine and 15, with the average age around 12 years. Signs your child’s period may start soon are:

Developing breasts
Growing pubic or underarm hair
Getting vaginal discharge (clear or white fluid).

Several factors can affect when a period first starts, such as genetics, weight, diet, stress and exercise levels.

It is best to speak to a doctor if your child has:

grown breasts before age seven
not had a period by the time they turn 15
not shown other signs of puberty by age 13.

Why do people get periods

The menstrual cycle

The menstrual cycle is the body’s way of preparing for a possible pregnancy. As hormone levels increase, the uterus (womb) lining thickens. About halfway through the month, the ovaries release an egg in a process known as ‘ovulation.’ If sperm fertilise the egg, pregnancy can happen. When there is no pregnancy, hormone levels fall, which makes the uterus lining break down and shed. This is a period.

A full menstrual cycle is the time from the first day of one period to the first day of the next period. The average cycle is 28 days long, but it can range from 21 to 45 days – especially in the first few years of having periods.

Tracking menstrual cycles

Some people track their menstrual cycle so they can better understand their body's patterns and prepare for their periods. This may include noting the start and end dates of each period, the flow intensity, and any symptoms. There are period-tracking phone apps that make this process easy, but a calendar or diary also works well.

When should I be worried that my child’s period has not come?

It is a good idea to speak with your child about seeing a doctor for advice if:

they have not had their first period by age 15.
it has been more than three months since their last period, they are not pregnant, and there is no clear reason.
they had regular periods, but the periods suddenly stopped or became very irregular.
they have other symptoms like unexpected hair growth, acne, weight changes, or changes in breast size.
you know they are sexually active, and their period is late or does not come at all. If this is the case, it is a good idea to encourage them to take a pregnancy test as well – even if they have been using contraception.

Common period symptoms

Periods are not just about bleeding – they can come with other physical and emotional changes. These changes are because of the rise and fall of hormones in the body during the menstrual cycle.

Some symptoms of periods include:

Physical symptoms

Cramps, like pain or tightness in the lower abdomen or back
Bloating
Tender breasts
Aches and pains
Headaches or migraines
Nausea and vomiting
Fatigue
Digestive changes like constipation or diarrhoea
Pimples and acne breakouts
Dizziness and feeling faint
Existing health problems, like asthma or chronic fatigue, may worsen.

Emotional symptoms

Feeling more sensitive or moody
Getting irritated easily
Feeling sad, down or anxious
Trouble concentrating
Problems sleeping.

For some people, these physical and emotional symptoms start a few days before a period. This group of symptoms is called premenstrual syndrome (PMS); it usually goes away once the period begins or ends.

Pain during periods

Mild to moderate cramps are common with periods – especially during the first few days. They usually feel like a dull ache or throbbing in the lower abdomen, back or thighs. Cramps are caused by the uterus tightening to help push out the blood and tissue.

If your child feels pain during their period that affects their everyday life, suggest they rest, use a heat pack and try gentle exercise. You may also want to offer them pain medicine. It is a good idea to speak with a doctor if these measures are not enough to help your child manage their pain.

When to get help

Your child’s pain is so bad that they cannot go to school or get out of bed.
Over-the-counter pain medicine like ibuprofen, naproxen or mefenamic acid does not help your child's pain, nausea or dizziness.
A heat pack, rest and gentle exercise do not help your child's pain.
Your child's cramps make them very nauseated, and/or they are vomiting a lot, and over-the-counter medicine does not help.
Your child feels dizzy and has fainted or almost fainted, and over-the-counter medicine does not help.
Your child's period seems extremely heavy.
Your child's period symptoms get worse over time.

Period products

There are many different products to help people manage their periods. The right ones for your child will depend on their body and lifestyle.

No matter which period products your child uses, they must change them regularly. This will stop leaks and help them maintain good hygiene.

Period products on blue background

Figure one: Mix of different period products, including a tampon (top left), menstrual cup (bottom left) and pads.

	What are they?	How do they work?	Pros	Cons
Pads	Pads (also called sanitary pads or menstrual pads) are strips that stick to the inside of underwear, catching and absorbing period blood.	Pads absorb period blood when it comes out.	Easy to use (great for beginners). Lots of different sizes and thicknesses. No internal insertion. Sold almost everywhere.	May feel bulky. Can move around if not stuck properly. Can leak during a heavy flow if not thick or absorbent enough. Not suitable for swimming.
Tampons	Tampons are small, tube-shaped products that are inserted into the vagina to soak up period blood from the inside.	Tampons are made of soft, absorbent material like cotton and expand as they absorb blood. They have a string that stays outside the body for easy removal.	Great for sports and swimming. Less bulky than pads. No feeling of wetness. Lots of different sizes and types – some with applicators to help insertion.	Needs to be correctly inserted to stop leakage. May not be comfortable, depending on anatomy. Very small risk of Toxic Shock Syndrome (TSS) if used continuously for long durations (should be changed every four to eight hours).
Period underwear	Period underwear looks and feels like regular underwear but has extra fabric layers to absorb period blood.	Period underwear soaks up blood like a pad.	Reusable and eco-friendly. Very comfortable – feels like regular underwear. No need to change throughout the day for a light to moderate flow. Can be worn alone (for a light or moderate flow) or as backup protection with other period products.	More expensive upfront. Need to be washed and dried properly. May not be absorbent enough for a very heavy flow.
Menstrual cups	A menstrual cup is a small, flexible silicone or rubber cup inserted into the vagina. It collects blood rather than absorbing it.	A menstrual cup sits inside the vagina and forms a seal so blood does not leak out.	Long-lasting and reusable. Good for the environment and cost-effective over time. Can be worn for up to 12 hours, depending on flow.	Takes practice to insert and remove. May be daunting to use at first. Needs to be cleaned well between uses. May get stuck and require a doctor to remove.

Benefits of different period products

Comfort: What feels comfortable is different for everyone. If your child is not sure, suggest they start with pads and try other options over time.
Lifestyle: Is your child active? Do they play sports? If so, tampons, menstrual cups, or period underwear may be a good fit.
Environmental impact: Reusable options like menstrual cups and period underwear create less waste.
Cost: Reusable options cost more at first, but they will save money in the long term.
Flow level: If your child has a heavier flow, they may need a combination of products or super-absorbent versions.

Many people mix and match period products. For example, they use pads at night, tampons during the day, or pair period underwear with a tampon for extra protection.

Your child might need to try a few products until they find what works for them.

Common questions about periods

Does my child need iron supplements when they get their period?

Most people do not need iron supplements during their period, but it depends on their bodies and diets. During periods, people lose a small amount of blood and, with it, some iron. They can usually make up for this by eating iron-rich foods like red meat, chicken, fish, beans, lentils, tofu, or fortified cereals. Eating vitamin C-rich foods like oranges, strawberries, or tomatoes can help the body absorb iron better.

Your child may need extra iron if their periods are very heavy, they feel tired all the time, or they get dizzy or out of breath easily. It is best to speak with a doctor before your child starts taking any supplements, as they may cause side effects.

My child’s period does not come at the same time each month. Is this normal?

It is normal for periods to come at different times each month – especially when it has just started. This is because the body is still getting used to new hormone patterns. Periods may come early, late, or not come for a month at all. Other factors can also impact how regular periods are, such as stress, illness, major weight changes or too much exercise. Over time, most people's cycles become more regular.

If your child’s periods used to be regular but have changed, they have not had a period for several months, or they often get periods more than once every 21 days, speak with a doctor for advice.

Why do people have other symptoms during their period if the change is happening in their uterus?

Hormones are chemical messengers in the body. Changing hormone levels cause the uterus to thicken, thin and break down, causing a period. However, they also send messages to other parts of the body. That is why some people have headaches, mood swings, nausea and other symptoms during their period.

What is menstrual suppression?

Menstrual suppression means using medicine (usually hormones) to change periods. It can make periods lighter, less frequent, or stop them temporarily. Medicine can also help people who find periods very hard to manage.

It is safe to use period-suppressing medicine if your child feels comfortable and a health professional agrees it is right for them. The blood does not 'build up' or cause harm, and it will not affect your child’s fertility. Remember that pregnant people do not usually have a period for nine months, and some who breastfeed do not get it back for several years.

There are many ways to suppress periods, like the pill, hormonal intrauterine devices (IUDs), injections, or implants. Everyone is different, so speak with your child and their doctor about what may work best.

Is it common to feel emotional during periods?

It is common to feel emotional during periods. Hormones like oestrogen and progesterone rise and fall throughout a person’s cycle, which may affect mood. Many people feel more sensitive, sad, anxious, or irritable in the days before their period starts.

If your child’s emotions are very intense or do not go away after their period finishes, it is a good idea for them to speak with a doctor or mental health professional, like a psychologist. They will be able to support your child and provide specialist advice.

What is endometriosis?

Endometriosis is a condition where tissue like the uterus lining grows outside of the uterus. The uterus lining changes during each menstrual cycle, getting thicker and thinner before the excess comes out as a period. For people with endometriosis, some excess lining attaches and grows in different parts of the pelvis and blood gets trapped. This can cause pain in some people.

Period pain is not always a sign of endometriosis. Your child should speak with a doctor if their period is affecting their everyday life or if they are worried for any other reason.

What is polycystic ovarian syndrome (PCOS)?

Polycystic ovarian syndrome (PCOS) is a hormonal condition. Many common symptoms of PCOS are also common during puberty, such as acne, irregular periods, excess body hair and extra follicles (fluid-filled sacs) on the ovaries. That is why it can be hard to tell if a young person has PCOS. Your child should speak with a doctor if they think they have PCOS symptoms.

Can the pill cause PCOS?

The pill does not cause PCOS. This is a common myth, but there is no scientific evidence to support it. The pill does the job of the ovaries by giving the body a steady supply of hormones like oestrogen and progestogen (a synthetic form of progesterone). When your child stops taking the pill, their body returns to making its own hormones. This may cause side effects like irregular periods and acne to come back. You and your child can always speak to a doctor about their symptoms for more information.

For more information

Developed by The Royal Children’s Hospital (RCH) Adolescent Medicine department, with input from the Gynaecology department. We acknowledge the input of RCH consumers and carers.

Reviewed August 2025

Please always seek the most recent advice from a registered and practising clinician.

Disclaimer

This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.

Updated July 2025

The Royal Children's Hospital Melbourne

Kids Health Info