What Is a Plan B Contraceptive?

Overview

The Plan B contraceptive, or emergency contraception, is used when the first form of birth control fails, or if no birth control was used. Plan B is not meant to be used as a daily form of birth control.

Ingredients

The National Women's Health Information Center states that Plan B contains high levels of progestin. Each pack contains two pills that are taken 12 hours apart.

Mechanism

Planned Parenthood states that the increased levels of progestin in Plan B suppresses ovulation, thickens the cervical mucus and thins the uterine lining, thus preventing pregnancy.

Effectiveness

Plan B needs to be taken 120 hours after intercourse, but is most effective in the first 72 hours. Planned Parenthood states that Plan B is 89 percent effective when taken within 72 hours.

Availability

As of November 2009, Plan B is available without a prescription to women 18 years and older. The National Women's Health Information Center states that the FDA approved for 17 year old women to obtain Plan B without a prescription, but as of November 2009 that has not gone into action.

Effect on Pregnancy

The National Women's Health Information Center notes that Plan B will not terminate an already existing pregnancy.

Side Effects

Very few women who take Plan B experience side effects; according to Planned Parenthood, less than one in four women feel ill after taking Plan B.