There are various forms of emergency contraception. The most common and easily tolerated is called “Plan B”. It is available without a prescription for anyone 18 years of age and older at most (but not all) pharmacies.
Those younger than 18 can also receive it with a prescription.
To prevent pregnancy, the first dose of pills must be taken by mouth as soon as possible, ideally within 3 days (72 hours), but no later than 5 days (120 hours) of having unprotected sex. A second dose is taken 12 hours after the first dose. The number of pills in the dose depends on the brand of pill used. For progestin-only pills, both doses can be taken at the same time or 12–24 hours apart.
For more information on emergency contraception, we encourage you to read the ACOG Brochure on Emergency Contraception.
Debra Ravasia, updated 2017