Is it safe for me taking birth control pills for severe menstrual cramps caused by endometriosis at age 42?

Yes and no. Birth control pills to help with endometriosis symptoms have estrogen and progesterone. Estrogen is associated with clots in the legs - what is called increasing hypercoagulation. If a person also smokes or has other conditions that increase likelihood of clots, taking pills will really increase the risk. Just being forty however is not necessarily something thatshould prevent taking pills.