Oral contraceptives can also be taken to decrease pain from endometriosis. There are pills that contain progesterone only for those extremely sensitive to estrogen. The failure rate for those pills is a bit higher but still less than condoms,diaphragms,spermacides, etc. Different pills contain variations on the "brand name" of the estrogen and progesterone they contain. A midwife recently told me the only reason the drug manufacturers make new pills every few years is to keep prices high. (as new pills are under patent and no generic can be made)