The FDA cautioned doctors Tuesday to be alert for deadly infections in women using the abortion pill RU-486, citing more deaths after its use.

At least five women, in the US alone, have died after taking the pill since it began selling in 2000, although the Food and Drug Administration admits there may be more contributing factors to blame.

Four deaths were caused by bloodstream infections, or sepsis, all occurring in women who took the pill.

The FDA issued a public health advisory forewarning doctors of the probable link and urging them to be on the lookout for infections in women who have used the Mifeprex abortion pill.

Some women may not have usual symptoms of sepsis, such as a fever.

Tuesday’s action comes just eight months after the FDA warned about two sepsis cases associated with Mifeprex, also called RU-486 or mifepristone. Additional sepsis cases were reported to the agency in April and June.

The drug, sold by Danco Laboratories, is designed to destroy the fetus up to 49 days after the beginning of the last menstrual cycle by blocking a hormone vital to the pregnancy. When followed by another medicine, misoprostol, the pregnancy is terminated.

In two of the infections, doctors discovered the bacterium Clostridium sordelli, a common germ not usually linked with infection.

Two other deaths associated with Mifeprex were cases of a ruptured ectopic, or tubal, pregnancy in October 2001. The drug is not to be used by women with suspected or confirmed ectopic pregnancies, a life-threatening condition in which the fertilized egg has implanted outside the uterus.

Other risks of Mifeprex and Misoprostol include incomplete abortion (with birth defects), sever hemorrhage, uterine rupture, and ulcers.