A cyst is basically a bubble—a collection of fluid with a thin wall around it. [Functional cysts are formed when a follicle (the fluid-filled sac that develops around an egg during ovulation) grows larger than expected](https://www.bedsider.org/features/223). Sometimes they can cause un-fun symptoms like abdominal discomfort, pelvic pain, pain during bowel movements, or pain during sex. Most cysts disappear on their own, but if they keep growing they can cause severe pelvic pain or pain that causes dizziness or fainting and comes with a fever or vomiting. If you have any of these severe symptoms, go see your health care provider ASAP. Some hormonal birth control methods—the ones that work by blocking ovulation—may mean fewer ovarian cysts. If you tend to get cysts, your provider might recommend you try a method like the pill, the ring, the patch, or the shot.