Mirena and breakthrough bleeding: what to know

Spotting may appear between expected periods, after sex, or in an irregular pattern. Hormonal contraception can make the womb lining thinner and less predictable, especially soon after insertion or when your bleeding pattern is changing. Bleeding can also have another cause, such as an infection or a polyp in the womb lining. Chlamydia can cause bleeding between periods or after sex, while endometrial polyps may bleed irregularly.

The pattern matters more than one isolated mark on toilet paper. Note whether the blood is pink, brown, or red, whether cramps or discharge occur, and whether the bleeding follows intercourse.

Keep a brief bleeding diary with dates, flow, cramps, discharge, intercourse, and any missed or late checks. Use pads if you need to judge the amount more easily. Do not remove or reposition the device yourself. Arrange a routine appointment if the pattern continues, returns after settling, or is affecting sex, sleep, work, or daily activities. A clinician may review the device, check for infection, and decide whether an examination or further testing is appropriate.

Seek urgent medical advice for very heavy bleeding, faintness, marked weakness, severe or worsening lower-abdominal pain, fever, or offensive discharge. Get prompt assessment if you may be pregnant, cannot feel the threads when you normally can, or feel hard plastic at the cervix. These features can point to a problem that should not wait for a routine review.

Ask what bleeding pattern is expected for your stage of Mirena use, whether you need an infection test or pelvic examination, and how to check the threads safely. Share any medicines, pregnancy possibility, pain, discharge, or bleeding after sex.