The U.S. Food and Drug Administration has approved the first generic version of emergency contraceptive Plan B (levonorgestrel) tablets.

The FDA said the generic product will be available by prescription only for women ages 17 and under.

Plan B was first approved in 1999 for prescription use for women of all ages. In 2006, Plan B was approved for non-prescription use for women ages 18 and older while still available as a prescription-only product for women ages 17 and under.

The FDA's Wednesday approval allows marketing of a prescription-only generic product for women ages 17 and under. The federal agency said no generic levonorgestrel product for emergency contraception can be approved for non-prescription use in women ages 18 and older until Aug. 24 when the marketing exclusivity for non-prescription use expires.

Generic levonorgestrel tablets 0.75 milligram are made by Watson Laboratories Inc. of Corona, Calif.

Plan B is manufactured by Duramed Pharmaceuticals Inc. of Cincinnati.