The U.S. Food and Drug Administration on Wednesday approved a generic version of the controversial Plan B morning-after contraceptive.

For now, the generic version, made by a unit of Watson Pharmaceuticals Inc., is available by prescription only for women 17 years old and younger, the FDA said in a press release.

The generic version will become available for women 18 and older without a prescription on Aug. 24, the date the marketing exclusivity for nonprescription use held by Duramed Pharmaceuticals Inc., subsidiary of Barr Pharma, maker of the original Plan B pill, ends.

The Plan B contraceptive has been shown to reduce the risk of pregnancy if taken within 72 hours after sexual intercourse.

The approval follows an earlier decision to allow women under 17 years old to use an over-the-counter brand-name version of the Plan B contraceptive. That move, ordered by a federal judge in March, rolled back the 18-year-old age imposed by the Bush administration.