The Morning-After Pill Is Birth Control Backup

The morning-after pill, or Plan B, was FDA-approved in 2006 to be sold without a prescription as emergency contraception. It's available at most pharmacies, but only to women over the age of 18. "Just ask the pharmacist and he'll give it to you," says Hilda Hutcherson, MD, an ob-gyn professor at Columbia University.

Plan B, which contains the same synthetic hormones found in birth control pills but in a higher dose, can prevent pregnancy from occurring if taken within 72 hours of unprotected sex. It may work up to five days after sex, but it works best when taken within 24 hours.

Since Plan B is more effective the sooner you take it, some health-care providers recommend having it on hand "just in case."

It should not be used as primary birth control, however. "Don't think, 'I'm only having sex four times a month, so I'll just take the morning-after pill every time,'" says Dr. Hutcherson. It's more expensive than other methods, may cause nausea, and will throw your cycles off. "Your body won't know what's going on," says Dr. Hutcherson.

Note: Plan B is not the same as RU-486, the abortion pill. In fact, if you take Plan B and you're pregnant already, says Hutcherson, "You're gonna stay pregnant. Not gonna help you."