What are side effects after starting ortho tri-cyclen in the first few months?

Unlikely but many: Most women using birth control pills have very few side effects. Most common side effects include: change of menstrual cycle, including irregular bleeding, or no periods. Swelling/edema, headaches, breast tenderness, nausea, weight gain. Rare but serious side effects include blood clots in legs/lungs. Beneficial effects may include normal menses, less cramping, lighter menstrual flow, .