Britannica Sources used in this answer

Why can copper IUDs cause heavier periods and more cramping?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Blister pack of 28 oral contraceptive pills arranged in four rows, with 21 white active pills followed by 7 orange inactive pills. Arrows indicate the order for taking pills. — birth control A 28-day package of birth control pills.

Copper IUDs are a highly effective form of birth control that function by releasing copper ions to impair sperm viability.12

While these devices are reliable, they are associated with specific side effects, including heavier, longer periods and increased cramping, particularly during the first few months following insertion. These symptoms often occur because the presence of the device and the release of copper ions can trigger inflammatory and immune responses within the uterus. In some instances, these inflammatory reactions may be severe enough to necessitate the removal of the device.12

In contrast, hormonal IUDs typically have the opposite effect, often resulting in lighter, less painful periods by thinning the uterine lining. If you are experiencing persistent or severe discomfort, it is important to consult a healthcare provider to discuss your symptoms and ensure the device is positioned correctly.12