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Irregular or absent periods

Everyone’s menstrual cycle is different, and cycles can change over time. At different life stages, some people have irregular periods or no periods at all.

Learn more about what causes irregular or absent periods, how to improve period regularity and when to see your doctor.

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What is a normal menstrual cycle?

The average length of a menstrual cycle is 28 days, and it’s common for periods to last from three to seven days.

What are irregular periods (oligomenorrhoea)?

Irregular periods are periods that don’t follow a typical pattern. This might mean your periods come earlier or later than expected, or they may be shorter or longer than usual.

Irregular periods can be frustrating because they are unpredictable, and you may not have period products when you need them. It can also be hard to plan for pregnancy.

What causes irregular periods?

For a year or two after you first get your period, it’s normal to have irregular periods. Usually periods become regular over time, but some people never have regular periods.

Your periods can become irregular as you approach menopause, after childbirth or after a miscarriage or abortion.

Irregular periods can also be due to:

Managing irregular periods

Your doctor might recommend medicine and lifestyle changes to help regulate your periods.


The oral contraceptive pill (the Pill) can help regulate periods and reduce period pain. There are different types of oral contraceptive pills with different doses of oestrogen and progesterone.

Metformin is a medicine used mostly for diabetes, but it can also help treat irregular periods for women with PCOS.

Lifestyle changes

A healthy lifestyle can help regulate your menstrual cycle. This includes eating a balanced diet, reducing stress, getting enough sleep and exercising regularly. Visit this government website to learn more about recommended exercise guidelines.

If your irregular periods are caused by PCOS, exercise and a 5% to 10% weight loss (if you are overweight) can help regulate your cycle.

Absent periods (amenorrhoea)

Absent periods (amenorrhoea) is when you don’t get your period at all. This can be short-term or long-term. If your period is late or has stopped, it’s important to check if you are pregnant.

Primary and secondary amenorrhoea

Primary amenorrhoea is when your period doesn’t start by the age of 16, but you have other signs of puberty such as pubic hair and breasts. Secondary amenorrhoea is when you miss your period for at least three months after previously having regular periods.

What causes absent periods?

The most common cause of absent periods is hormonal imbalance. This may be due to:

  • conditions such as PCOS
  • pituitary or thyroid disease
  • weight gain
  • an abnormality that develops at birth (congenital disorder)
  • weight loss
  • excessive exercise
  • anxiety or stress
  • travel
  • dieting or eating disorders
  • menopause.

Absent periods can also be caused by a rare condition called ‘Asherman’s syndrome’, where scar tissue forms in the uterus or on the cervix. Scarring can happen after surgery (e.g. a hysteroscopy, dilation and curettage (D&C), or caesarean section).

Radiation treatment may also lead to scarring.

Asherman’s syndrome can cause very light periods, absent periods, severe cramping or pelvic pain. It can also make it hard to become pregnant.

Managing absent periods

Depend on the cause, your doctor might recommend:

  • hormonal therapy
  • certain medicines
  • lifestyle changes
  • nutritional advice
  • surgery.

If the cause is related to an eating disorder, your doctor may recommend specialist care.

When to see your doctor

See your doctor if:

  • your periods have not started by the age of 16 to 17
  • you have missed three or more periods in a row
  • you have had less than nine periods in a year
  • you have noticed changes in the pattern of your periods.

There are other reasons why you might need to see your doctor about your periods.

It’s a good idea to record information about your period to discuss at your appointment. For example, when you get your period, the length and heaviness of your period and how your periods impact your life.

This con­tent has been reviewed by a group of med­ical sub­ject mat­ter experts, in accor­dance with Jean Hailes pol­i­cy.

Tejpal C, Poudel I, Jahan N. Is Metformin the Answer for Distressed Females with Menstrual Irregularities?. Cureus. 2019;11(8):e5460. Published 2019 Aug 22. doi:10.7759/cureus.5460
Last updated: 
22 April 2024
Last reviewed: 
25 March 2024

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