My GF has an irregular menstrual cycle, roughly once every 2 months.
All oral contraceptives have some side effects.
Estrogen-progestin pills have the most side effects. Progrstin only ones have fewer serious side effects but are more likely to cause irregular periods. See the FAQ's about the Pill for more info on side effects. My GF has an irregular menstrual cycle, roughly once every 2 months. All oral contraceptives have some side effects.