Heavy period on blood thinners: what to know

Anticoagulant medicines reduce the blood's ability to form clots, so menstrual bleeding may become heavier or last longer. Other causes can occur at the same time, including fibroids, adenomyosis, endometrial polyps, endometrial hyperplasia, perimenopause, or polycystic ovary syndrome. Ongoing loss can contribute to iron deficiency anaemia.

The correct response depends on why the medicine was prescribed, which medicine and dose you take, your bleeding pattern, and other medicines. A prescriber may review blood tests, iron status, contraception, and options to control bleeding without increasing clot risk.

Contact the clinician managing your anticoagulant or a gynaecology service and explain how the bleeding has changed. Keep taking the prescribed medicine unless that clinician gives different instructions. Keep a record of flow, clots, dizziness, breathlessness, and missed doses. Check before using over-the-counter pain or bleeding medicines, because some can interact with anticoagulation or affect clotting.

Seek urgent help for bleeding that is rapidly soaking protection, faintness, worsening weakness, shortness of breath, chest pain, severe headache, severe abdominal pain, or possible pregnancy. Tell the healthcare team which blood thinner you take and when you last took it.

Ask whether the flow could be causing iron deficiency, whether tests are needed, and which menstrual treatments are compatible with your blood thinner. Ask what to do if you miss a dose or the bleeding suddenly increases.