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Periods, absent


Not having regular periods is usually considered a cause for concern in girls and women who:

  • have gone through puberty, which normally happens around the age of 12–13
  • are not pregnant
  • have not had surgery to remove part or all of their womb
  • have not yet gone through the menopause, which normally happens in the late 40s or early 50s

The medical name for absent or missing periods is amenorrhoea.

When to seek medical advice

Missing periods can be a sign of an underlying health problem. It is recommended that you visit your GP if:

  • You have not had a period by the time you are 14 and you show no other sign of sexual development (such as breast growth and pubic hair) or you have not had a period by the time you are 16 but other signs of sexual development are normal (doctors call this primary amenorrhoea).
  • You previously had regular periods but have now not had a period for six months in a row (doctors call this secondary amenorrhoea). This is the most common type of absent periods.

What causes absent periods?

If you've never had a period

Possible causes of primary amenorrhoea include:

  • delayed periods – some girls just take longer than average to have their first period
  • problems with the development of the reproductive system

If you used to have periods but they've stopped

A health problem is usually the cause of your periods stopping. The five most common conditions causing secondary amenorrhoea are:

  • polycystic ovary syndrome (PCOS)
  • hypothalamic amenorrhoea – where the part of the brain that regulates the menstrual cycle stops working properly (it's thought to be triggered by excessive exercise, weight loss and stress)
  • hyperprolactinemia – where a person has abnormally high levels of a hormone called prolactin in their blood
  • the ovaries stopping working properly (ovarian failure), even though the woman has not yet gone through the menopause
  • hormonal conditions such as having an overactive thyroid or underactive thyroid

Read more about the potential causes of absent periods.

Treating absent periods

The treatment for missing periods will depend on the cause.

For example, PCOS can often be controlled using hormonal treatments, and women with hypothalamic amenorrhoea will have regular periods if they cut down on exercise and eat more.

However, some causes of absent periods, such as ovarian failure, cannot be successfully treated and the woman will become infertile.

Read more about the treatments for absent periods.

Who is affected?

Secondary amenorrhoea is relatively common. It is estimated that around 1 in 25 women will be affected by absent periods at some point in their lives.

It is more common in teenage girls and younger women, and can be much more common in certain groups, such as professional athletes, dancers and gymnasts.
Not starting your periods is much less common, affecting an estimated 1 in every 300 girls and women.

If you have other problems with your periods, we also have information on:

The menstrual cycle

Periods are part of the menstrual cycle.

Roughly every 28 days, a woman’s ovaries will release eggs (as long as she has not gone through the menopause).

The lining of the womb will thicken to prepare for the eggs. If the eggs are not fertilised by sperm, this thickened lining will break down, resulting in bleeding from the vagina. This is a period.

The menstrual cycle is very sensitive to the effects of certain hormones, which is why hormonal conditions are a common cause of absent periods.

Read more about periods.

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Some girls have a temporary delay in starting their periods. Absent periods can also be the result of a health problem.

If you've never had a period

The medical term for not having a period despite being the expected age is primary amenorrhoea.

There can be different causes of primary amenorrhoea depending on whether you also have other signs of sexual development, such as breast growth, pubic hair and development of your genitals.

These are the main reasons for your periods being absent if you do have other signs of sexual development:

  • delayed periods – some girls take longer than average to have their first period, which is often the case if their mother or older sisters also took longer 
  • birth defects – although it's very uncommon, baby girls can have problems in the development of their reproductive system, such as having no womb, ovaries or vagina
  • androgen insensitivity syndrome – a rare genetic condition (affecting around 1 in every 20,400 births) in which a baby can be born with external female genitals but internal male genitals

If you do not have any other signs of sexual development, then possible causes for your absent periods are:

  • severe weight loss, often related to an eating disorder such as anorexia nervosa
  • stress 
  • Turner syndrome – a genetic condition, affecting around 1 in every 2,000 girls, which causes those affected to be born with ovaries that do not produce the hormones required to trigger the menstrual cycle
  • Kallmann syndrome – another rare genetic condition (affecting around 1 in every 10,000 births) where hormones that normally trigger sexual development are missing

If you used to have periods but they've stopped

Common causes for periods suddenly stopping (secondary amenorrheoa) are described below.

Unexpected pregnancy

Becoming pregnant without realising it is a surprisingly common cause of an absent period.

This can often occur when your method of contraception fails without you realising it.

Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common condition responsible for as many as one in three cases of missing periods.

The features of PCOS include:

  • a number of cysts (fluid-filled sacs) developing around the edge of the ovaries (polycystic ovaries)
  • failure of the ovaries to release eggs (ovulate)
  • a higher level of male hormones than normal, or male hormones that are more active than normal

As well as causing absent periods, other symptoms of PCOS include excessive body hair, problems getting pregnant and weight gain.

Hypothalamic amenorrhoea

The menstrual cycle is regulated by part of the brain known as the hypothalamus. This produces hormones that cause the ovaries to release eggs.

In cases of hypothalamic amenorrhoea, the hypothalamus stops producing these hormones and the menstrual cycle stops.

Exactly why the hypothalamus does this is unclear, but evidence has identified three triggers of hypothalamic amenorrhoea:

  • excessive weight loss – having a body mass index (BMI) of 19 or less can often trigger hypothalamic amenorrhoea (use the BMI calculator to check your BMI)
  • excessive exercise
  • stress

Hypothalamic amenorrhoea is particularly widespread in women whose profession requires a combination of physical fitness and maintaining a low body weight, such as athletes and dancers.

Even if you are not concerned about not having a period, you should still seek medical advice if you think you have hypothalamic amenorrhoea, as it can lead to brittle bones (osteoporosis) and put you at risk of a bone fracture.


Hyperprolactinemia means you have excessively high levels of a hormone called prolactin in your body.

High levels of prolactin are normally only required after birth, as they help stimulate the production of breast milk. Having high levels at other times can disrupt the normal menstrual cycle and lead to absent periods.

Hyperprolactinemia is thought to affect around 1 in every 200 women and can have a wide range of causes, such as:

Hyperprolactinemia can also arise as a side effect of some treatments and medications, such as:

  • radiotherapy 
  • antidepressants 
  • calcium channel blockers – a medication used to treat high blood pressure
  • omeprazole – a medication used to treat stomach ulcers

Women who regularly use the drug heroin often develop hyperprolactinemia.

Ovarian failure

Ovarian failure is when the ovaries stop producing eggs in women who should still be young enough to ovulate (usually 40 or younger).

It is estimated that ovarian failure affects:

  • 1 in every 1,000 women aged 30 or younger
  • 1 in every 250 women aged 30–35
  • 1 in every 100 women aged 40

It is thought that many cases of ovarian failure are caused by the immune system malfunctioning and attacking the ovaries.

Again, you should seek medical advice if you suspect you have ovarian failure, even if you are not concerned about having periods. This is because having this condition can put you at risk of osteoporosis and heart disease.

Thyroid conditions

The thyroid gland is found in the neck. It produces hormones that are released into the bloodstream to control the body's growth and metabolism. They affect processes such as heart rate and body temperature, and help convert food into energy to keep the body going.

In some women, the thyroid gland can:

  • produce too many hormones – this is known as having an overactive thyroid gland or hyperthyroidism
  • not produce enough hormones – this is known as having an underactive thyroid gland or hypothyroidism

Both hyperthyroidism and hypothyroidism can cause absent periods.


Some women who use a contraceptive implant, contraceptive injection or (less commonly) the contraceptive pill may find that their periods become irregular or stop all together.

Your periods should start again once you stop using these forms of contraception, although occasionally these effects can persist.

If you have not been using these types of contraception for six months or more and you still have not had your period, contact your GP for advice.

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You should see your GP if any of the following conditions apply:

  • You are 14 or older, have not started your periods and have not started physical sexual development, such as breast growth or pubic hair (read more about girls during puberty). 
  • You are 16 or older and have not started your periods but have the normal physical features of puberty (primary amenorrhoea).
  • You used to have periods but have not had one for the last six consecutive months (secondary amenorrhoea).

Your GP will determine whether you have primary amenorrhoea (you haven't started your periods) or secondary amenorrhoea (your periods have stopped). They will then try to identify the cause of your absent periods.

First, you may be offered a pregnancy test to rule out pregnancy.

Your GP will also take full details, including noting your medical history, work and activity, family medical history, sexual history and any emotional upsets or changes in body weight. They will also assess whether you are going through the normal physical stages of puberty.

  • If your GP diagnoses primary amenorrhoea, you may be referred to a gynaecologist (a specialist in treating conditions that affect the female reproductive system).
  • If your GP diagnoses secondary amenorrhoea, they can usually identify the underlying cause and treat it. In some cases, they may refer you to a gynaecologist or endocrinologist (a specialist in treating hormonal conditions).

Referral if you've never had a period

Your GP may diagnose primary amenorrhoea and refer you to a gynaecologist if:

  • You have not started your periods by the age of 14 and your body shows no signs of going through puberty.
  • You have normal features of puberty but have not started your periods by the age of 16.

Your specialist may give you a full gynaecological examination and carry out various tests, including:

  • blood tests to determine your levels of prolactin, thyroid-stimulating hormone, follicle-stimulating hormone and luteinising hormone (abnormal amounts of these may be the cause of your missing periods)
  • a pelvic ultrasonographycomputerised tomography (CT) scan or MRI scan – these scans take detailed pictures of the inside of your body and reveal any problems with your vagina or womb

Referral if you used to have periods

Your GP may diagnose secondary amenorrhoea and refer you to a gynaecologist or endocrinologist if:

  • the cause cannot be identified
  • the cause needs to be confirmed
  • specialist treatment is needed, for example for infertility

Possible causes that need confirmation are:

You may be referred to a dietitian if you are underweight (have a body mass index of less than 19), or to a psychiatrist or psychologist if your GP thinks you have an eating disorder.

Assessing your sexual development

Your doctor will assess your development through puberty by using the following guide:

  • Stage 1: breasts have started to develop and pubic hair has started to grow.
  • Stage 2: breast buds have formed and there are long, downy pubic hairs around the genitals.
  • Stage 3: breast buds are larger and pubic hair is growing.
  • Stage 4: breasts are in a "mound" form and pubic hair is in the triangular shape, but not fully grown.
  • Stage 5: breasts are fully formed and pubic hair is adult in shape, quantity and type, and spread to the inner thighs.
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If you've never had a period

If you have not had your period by the age of 14 and are showing no other signs of sexual development, you will probably be referred to an endocrinologist (a specialist in treating hormonal conditions).

This is because there is a good chance that your absent period is caused by problems with your hormones.

If you have not had your period by the age of 16 but are showing signs of sexual development, you will probably be referred to a gynaecologist (a specialist in treating conditions that can affect the female reproductive system). This is because there is a good chance that your absent periods are caused by problems with your reproductive system, such as your ovaries or vagina.

It is hard to predict what treatment you will be offered as this will depend on what the tests and examinations reveal. Read more about diagnosing absent periods.

Possible options include:

  • a "wait and see" approach if it is thought that your period is delayed rather than missing
  • surgery to correct problems with your reproductive system
  • hormone therapies to treat Turners syndrome or Kallmann syndrome (replacing the hormones that should be produced by your body)

Not every case of primary amenorrhoea can be treated. For example, there is no way of making you have periods if you have androgen insensitivity syndrome.

If you used to have periods but they've stopped

As with primary amenorrhoea, the recommended treatment options for secondary amenorrhoea will depend on the underlying cause. The most common causes and their recommended treatments are outlined below.

Polycystic ovary syndrome

Polycystic ovary syndrome can have a range of treatments, but hormone therapy is often recommended to restore a normal menstrual cycle.  Read more about treating polycystic ovary syndrome.

Hypothalamic amenorrhoea

Hypothalamic amenorrhoea (absence of periods caused by extreme weight loss, excessive exercise or stress) can be treated by addressing the underlying cause.

If your symptoms are the result of weight loss, you may be referred to a dietitian, who can advise you on safe ways of regaining a healthy weight.

If your weight loss is the result of an eating disorder, such as anorexia, you will need to be referred to a psychiatrist (doctor who specialises in treating mental health conditions) who has experience in treating eating disorders. Read more about treating anorexia nervosa.

If your symptoms are the result of excessive exercise, you will need to reduce your levels of physical activity. If you are a professional athlete or similar, you may benefit from a referral to a doctor who specialises in sports medicine. They should be able to advise you about how you can maintain fitness and physical performance without disrupting your periods.

If your symptoms are the result of stress, a type of talking therapy called cognitive behavioural therapy (CBT) might help. CBT is a type of therapy that aims to help you manage your problems by changing how you think and act. Read more about treating stress.


The treatment for hyperprolactinemia (where a person has abnormally high levels of a hormone called prolactin) will depend on the underlying cause.

For example, if hyperprolactinemia is the result of a brain tumour, then surgery, radiotherapy or chemotherapy may be required to remove or shrink the tumour. If hyperprolactinemia occurs as a side effect of a medicine, your medication may need to be reviewed.

Thyroid conditions

Treatment options for an overactive thyroid gland include thioamide medication, which helps reduce thyroid activity, and radiotherapy, which can be used to reduce the size of the thyroid gland.

Treatment options for an underactive thyroid gland include a medication called levothyroxine, which can stimulate thyroid activity.

Read more about treating an overactive thyroid and treating an underactive thyroid.

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