Is it normal to have a long period while using and IUD as a birth control?

Yes, the copper IUD (intrauterine device), brand-named Paragard in the US, can cause irregular periods, heavier periods and increased cramps. These side effects are more common in the first six months after the IUD is inserted. The Mirena IUD, which contains levonorgestrel, may cause irregular periods in the first months of use, but over time you can expect fewer periods and less bleeding.