This document summarizes injectable contraceptives. There are two main types - progestogen-only injections which are effective for 2-3 months, and combined injections containing estrogen and progestogen effective for 1 month. Progestogen-only injections like DMPA are widely used and provide highly effective contraception through thickening cervical mucus and impairing ovulation. Combined injections like Mesigyna also suppress ovulation and are effective immediately with 1 injection. Common side effects include menstrual irregularities but are generally safe and reversible methods of contraception.