The first government-approved treatment for baldness could rejuvenate the hairlines of many of America's estimated 30 million balding men, but officials caution the prescription drug "will not work for everyone."

The Food and Drug Administration gave the The Upjohn Co. permission Wednesday to market Rogaine Topical Solution, a lotion containing 2 percent of the active ingredient minoxidil, originally a high-blood-pressure medicine."This is the first established product for baldness," said FDA spokesman Brad Stone, referring to a market rampant with quack remedies aimed at men desperate to keep from becoming bald.

Clinical studies showed Rogaine produced moderate hair growth on the crown of the head in 31 percent of balding men and dense hair growth in another 8 percent, the FDA said.

But little or no hair growth was reported in 61 percent of test subjects.

The FDA found minoxidil lotion, which is rubbed directly on the head, had little or no effect on frontal baldness. In addition, "stopping Rogaine use will lead to the loss of new hair within a few months," the spokesman said.

Rogaine also does not produce overnight miracles. Stone said it takes about four months of twice-daily applications of the lotion before hair growth can be expected.