abnormal uterine bleeding
"I started the shot about 4 months ago. The first few weeks it was great and I loved not having to take a pill everyday. Then I started spotting, but I knew it was a side effect and thought it would stop. The spotting/bleeding continued for 3 months, on and off. When I would think it stopped, I'd have sex and it would start bleeding during or after sex. After the 3 months ended I was so excited that I wouldn't have to ruin anymore underwear and buy any more tampons but I was wrong, every now and then I spot and bleed during or after sex. It is annoying and inconvenient. This is a great thing if you really don't want to get pregnant but if it is just for cramps and heavy periods I do not recommend."