But new research finds women receiving the shot should pay extra attention to their bone health.
Doctors at the University of Texas followed 95 women using Depo-Provera for two years and periodically assessed their bone strength.
Half of users had a sizeable drop in mineral density in their spine or hip bones, which could lead to fracture risk.
The shot causes a long-term disturbance in hormones, which both prevents pregnancy and causes bone changes.
Past research suggests that the bone strength typically recovers when women stop using Depo- Provera, but this can't be guaranteed and experts advise women to limit the duration they are on the shot to no more than two years.
Smokers run particular risk for bone loss, so women can reduce their odds by not smoking and doctors recommend taking calcium and vitamin D to boost bone strength as well.
The research was published in the journal Obstetrics & Gynecology.