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What causes bleeding between periods?

There are many different causes of bleeding between periods. Some may not be anything to worry about, but seek medical advice if you’re concerned.  

Hormonal contraceptives

Irregular bleeding, such as bleeding between periods, is common during the first three months of starting hormonal contraception, such as the:

If you’re concerned about bleeding, or it lasts longer than three months, you should seek medical advice.

You may also bleed between periods if you:

Other causes

Some other causes of irregular or abnormal bleeding include:   

  • taking the emergency contraceptive pill  
  • injury or disease of the vagina – for example, from having rough sex, an infection, ulcer or varicose veins 
  • a recent abortion – if you’re bleeding heavily, seek medical advice 
  • sexually transmitted infections (STIs) such as chlamydia – if you’ve recently had unprotected sex with a new partner, it’s a good idea to get tested    
  • reproductive hormones not working normally – this is common in women approaching the menopause or in women with polycystic ovary syndrome (PCOS)
  • stress
  • vaginal dryness
  • harmless changes to the cervix (neck of the womb) – this may be called ectropion or cervical erosion
  • cervical cancer – if you’re aged 25-64, you should be having regular cervical screening tests to detect any changes to your cervix. Even if you are up to date with screening tests you should seek advice about irregular bleeding, especially bleeding after sex, to eliminate the possibility of cervical cancer. 
  • womb (uterus or uterine) cancer – this is more common in women who have been through the menopause, and most cases of endometrial cancer are diagnosed in women aged over 50. Women over 40 with bleeding between periods should see their GP to eliminate the possibility of uterine cancer.
  • cervical or endometrial polyps (benign or non-cancerous growths in the womb or the lining of the cervix)

When to seek medical advice

If you’re concerned about your bleeding, you should:

  • see your GP
  • visit a sexual health or GUM (genitourinary medicine) clinic

A healthcare professional will talk to you about your symptoms. Depending on your situation, they may suggest carrying out some tests, such as:

  • tests for STIs, which may include an examination of your genitals
  • a pregnancy test
  • a cervical screening test, if you’re aged 25-64 and not up-to-date with these 
  • a pelvic ultrasound scan 

To diagnose some conditions, you may need an examination, such as: 

  • a speculum examination – a speculum is a medical instrument that is inserted into your vagina 
  • an internal examination of your vagina with the fingers (bimanual examination)  

Read the answers to more questions about women’s health

Further information:


Menstrual cycle: animation

This animation explains in detail how the menstrual cycle works.

Media last reviewed: 21/02/2015

Next review due: 21/02/2017

Page last reviewed: 03/11/2014

Next review due: 15/11/2016