There are some cases where you should not get the IUD, for instance:

- If you're pregnant or think you might be pregnant.

- If you have any uterine abnormalities that would make it hard for the IUD to stay in place (your doctor can check for this).

- If you have acute pelvic inflammatory disease (PID) or a history of PID.

- If you have any unexplained genital or uterine bleeding.

- If you've had postpartum endometritis or an infected abortion in the past three months.

- If you have severe liver disease.

- If you have breast cancer or a history of breast cancer, you should not get the hormonal IUD, but your doctor might suggest the copper IUD.

- If you have any untreated pelvic infections (like chlamydia) or are prone to pelvic infections, you may not be a good candidate for either IUD. Talk to your doctor about this history before getting an IUD.

- If you have Wilson's disease (a rare disorder where copper can accumulate in the body) you cannot get the copper IUD.

This is not an exhaustive list, so make sure to go over a detailed medical history with your doctor before deciding on the IUD.