It takes 12 weeks for Depo to leave the system after a single injection. It mainly breaks down in the liver, with its metabolites eliminated from the body through urine and feces, according to Pharmacia and Upjohn Company, a Pfizer subsidiary.
According to Pfizer, Depo is a long-acting contraceptive, containing medroxyprogesterone acetate. The National Health Service of the UK lists the drug’s higher than 99 percent efficiency, long duration and protection against some forms of cancers as the main benefits of Depo. However, the NHS also makes clear that it does not provide a defense against sexually transmitted diseases and does have a range of side effects. Potential side effects include irregular periods, weight gain, headaches, lowered sex drive and mood changes.