Study guide for medical terminology & coding · Bleeding between periods? Read the patient guide
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Patient guide

Bleeding between periods on birth control

By the Metrorrhagia.com editorial teamUpdated Medical review pending
Illustration of a generic, unbranded pill pack beside a desk calendar, a glass of water and a phone reminder.

Educational content for students. Not medical or coding advice. Having symptoms? See the patient guide.

On this page
  1. Why it happens
  2. Still get checked if
  3. Sources

Bleeding between periods ("breakthrough bleeding") is a well-known side effect of hormonal contraception [ACOG], and the NHS lists hormonal contraception such as the pill as a common cause of bleeding between periods [NHS].

Why it happens

Hormonal methods change the lining of the uterus, which can shed unpredictably, especially in the first months on a new method. The copper IUD can cause heavier periods, especially in the first year [ACOG].

Still get checked if

  • It starts after months of no problems on the same method.
  • You've missed pills or might be pregnant. Take a pregnancy test.
  • It happens after sex, or with pain, unusual discharge or fever. These can be signs of infection such as chlamydia [NHS].
  • It's heavy, or it worries you.

Don't stop your contraception without a plan. Talk to a clinician about options [NHS contraception guide].

Sources

  1. Abnormal Uterine Bleeding (FAQ095) American College of Obstetricians and Gynecologists, reviewed Aug 2025
  2. Vaginal bleeding between periods or after sex NHS, reviewed Aug 2024
  3. Contraception guide NHS

We link to primary medical sources so you can check our work. See the editorial policy and the full reference list.