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:

miss any combined pills
miss any progestogen-only pills
have a problem with your patch or vaginal ring
are on the pill and are also sick or have diarrhoea
have taken certain prescription medicine or St John's Wort (a herbal remedy) and you're using the pill, patch, ring or implant
miss out your pill-, patch- or ring-free week

Some other causes of bleeding between periods include:

taking the emergency contraceptive pill
injury of the vagina – for example, from having rough sex
having a recent abortion – seek medical advice if you're bleeding heavily
sexually transmitted infections (STIs) such as chlamydia – it's a good idea to get tested if you've recently had unprotected sex with a new partner
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 neck of the womb (cervix) – this may be called cervical ectropion or cervical erosion
cervical cancer – if you're aged 25 to 64, you should be having regular cervical screening tests to detect any changes to your cervix; even if you're up-to-date with screening tests, you should seek advice about irregular bleeding, particularly bleeding after sex, to eliminate the possibility of cervical cancer
womb (uterus or uterine) cancer – this is more common in post-menopausal women, and most cases of endometrial cancer are diagnosed in women over the age of 50; see your GP if you're over 40 and have bleeding between periods 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

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

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 to 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's inserted into your vagina to examine your vagina and cervix
an internal examination of your vagina with the fingers (bimanual examination)