Irregular periods

Irregular periods means a variation in the length of time between your periods from one month to the next that's more than a few days.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2021


While a small difference is quite normal for most women, it could be a sign that you have a health issue or medical condition that can be treated.

Causes of irregular periods

On average, periods happen every 28 days and last for about five days. However, it's common for the time between periods to be longer or shorter than this or to last longer than seven days. You shouldn’t worry if:

  • You're still going through puberty
  • You've always had slightly irregular periods of a few days

You'll probably have irregular periods if:

  • The variation in time between periods is seven days or more
  • The length of time between your periods keeps changing

Talk to your doctor if you’re concerned about symptoms

Book an appointment with a Spire GP today.

Conditions related to irregular periods

There are many reasons for irregular periods, these include:

  • Being overweight
  • Eating disorders, such as anorexia
  • Being stressed
  • Going through puberty
  • Pregnancy - you can still experience bleeding in early pregnancy
  • The contraceptive pill or intrauterine system (IUS)
  • Starting the menopause

Irregular periods could also be a sign of an underlying medical conditions such as:

Getting a diagnosis for irregular periods

Keep a note of when your periods start, then count the days between them, to see if this varies.

While irregular periods aren't always a sign of a medical problem, it's a good idea to visit your GP to rule out or identify possible health issues, especially if:

  • You're under 45 and your periods suddenly become irregular
  • You have irregular periods and are finding it hard to get pregnant

Also, tell your GP if you have heavy irregular periods, are bleeding between periods or have symptoms such as pain or discomfort.

In order to make a diagnosis, your GP may:

  • Measure your blood pressure and weight
  • Arrange a blood test to check your hormone levels
  • Assess your stress level
  • Ask if you might be pregnant
  • Perform an internal examination
  • Send you for an ultrasound scan of your womb (uterus)

You may be referred to a gynaecologist if your doctor feels you need further tests or specialist treatment.

Treatments for irregular periods

Treatment of irregular periods depends on the underlying cause of the problem. For example, you may be offered:

  • Hormone therapy, such as the contraceptive pill or hormone replacement therapy
  • Thyroid treatments

Getting pregnant can be difficult for some women with irregular periods, but hormone or fertility treatments can help.

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