A woman may be able to have unprotected sex as soon as she gets the Depo shot, depending on when during her cycle the shot is given.
If the first shot is administered within the first 7 days after the start of a woman’s period, she is protected from pregnancy immediately and can have unprotected sex right away. If the Depo shot is given during any other time in the menstrual cycle, another form of birth control, such as a condom, is needed for the first week after getting the shot.
Women should get a new shot every 12-13 weeks (about every 3 months, or 4 times per year) to stay protected against unwanted pregnancy.
What Is the Depo Shot?
How Effective is the Depo Shot Birth Control?
The Depo shot contains the female hormone progestin which prevents pregnancy by preventing the release of an egg from the ovary (ovulation). If a woman doesn’t ovulate there’s no egg to meet the sperm and no pregnancy can occur.
The Depo shot also causes cervical mucus to thicken, which helps prevent sperm from getting through. If the sperm can’t get through, it can’t reach an egg, and pregnancy cannot happen.