What should you know about reason for breakthrough bleeding?

It may look like light spotting or bleeding outside your expected period. The timing, amount, colour, associated pain, pregnancy possibility, and medicines you use help a clinician work out the next step.

Starting, stopping, missing, or changing hormonal contraception can temporarily alter the lining of the womb. Bleeding can also occur with an intrauterine device, emergency contraception, or medicines that affect clotting. A pregnancy-related cause should be considered when pregnancy is possible, particularly if bleeding comes with one-sided pain, dizziness, or shoulder-tip pain.

Infections affecting the cervix, including chlamydia, can present with bleeding between periods or after sex. Endometrial polyps can also present with irregular bleeding. Other possibilities include changes around menopause, thyroid or other hormone conditions, and irritation after sex. A pattern that continues, returns, or changes deserves an assessment even when the bleeding is light.

Record when the bleeding starts and stops, how often you change a pad or liner, whether it follows sex, and any pain, discharge, fever, or dizziness. Note contraception, recent changes in medicines, and the date of your last expected period. This information can make the consultation more focused.

Take a pregnancy test if pregnancy is possible. Arrange a routine appointment if the bleeding is unexplained, keeps returning, occurs after sex, or comes with unusual discharge or pelvic discomfort. Do not stop prescribed contraception or other medicine without advice; a clinician can discuss whether the method or dose needs review.

Seek urgent medical help for heavy bleeding, severe or worsening pelvic pain, fainting, marked dizziness, fever, or feeling very unwell. If pregnancy is possible, bleeding with one-sided abdominal pain, shoulder-tip pain, faintness, or collapse needs urgent assessment because an ectopic pregnancy can be dangerous.

Contact a clinician promptly if bleeding happens after menopause, follows sex repeatedly, or is accompanied by pelvic pain, pain during sex, or foul-smelling discharge. The amount of bleeding alone does not identify its cause, so describe the pattern and associated symptoms clearly.

You could ask: Could my contraception or medication explain this pattern? Do I need a pregnancy test or testing for an infection? What examination or scan would help identify a cervical or womb cause? Which changes in bleeding should prompt earlier contact?