NEW YORK (AP) _ It grows hair for only about one in four people and it'll cost you $180 and six months to find out if you're among the lucky.

Nonetheless, the 60 million Americans who suffer hair loss can now buy Rogaine _ the first medically proven baldness drug _ without a prescription.

Pharmacia & Upjohn Inc. on Wednesday began shipping the over-the-counter version of Rogaine in blue and pink boxes with separate instructions on how it works for men and women.

Hair-impaired consumers should start seeing it in the shampoo sections of pharmacies, supermarkets and department stores in a few days, with a heavy advertising campaign to follow.

After eight years of prescription sales, the Food and Drug Administration in February approved nonprescription use of Rogaine at the same potency.

The drug thus became the latest high-profile prescription-to-OTC switch as drug companies capitalize on an increasing desire of Americans to medicate themselves.

Rogaine follows such successes as the painkillers Tylenol and Advil, and more recently Pepcid AC and Tagamet HB for upset stomachs.

Industry analysts are skeptical, however, on whether Rogaine will do the same.

Rogaine racked up a respectable $124 million in sales during 1995, but sales have stagnated in recent years, which analysts blame on its high failure rate.

While Pharmacia & Upjohn says tests claim up to 26 percent of users see moderate to heavy hair growth after four months, analyst James Keeney of the securities firm Rodman & Renshaw said the real number is closer to 10 percent.

A sidewalk survey of thin-topped New Yorkers indicated some see little need for the product, even if it now is easier to buy.

``Probably not,'' said Pete Dolan, when asked if he'd try it. ``I'm sure some men are vain enough for it to bother them, but my girlfriend thinks I'm good looking just the way I am,'' said Dolan, 32, a multimedia software designer from the borough of Staten Island.

``Actually I'm planning to shave my head this summer,'' said Marvin Kram, 35, a computer programmer from Manhattan. ``It's fashionable and my wife thinks some of the sexiest guys on TV are bald.''

Opinions like those aside, Pharmacia & Upjohn is counting on America's vanity to increase total annual revenue from the drug _ even though the price of one bottle, a one-month supply, has been cut to roughly $30 from $55.

Although prescription Rogaine's patent ran out in February, the switch to OTC status gives the company three more years of exclusive sales before generic copies are allowed.

Dr. Nia Terezakis, a New Orleans dermatologist and professor at Tulane and Louisiana State universities, said many of Rogaine's problems stem from unrealistic expectations and incorrect use.

``It takes a person several years to even notice their hair has thinned and you have to lose almost half the volume to even notice. Once people notice they want the problem gone overnight,'' she said.

Rogaine only works well with people in the early stages of hair loss _ and the loss must be caused by hereditary factors, not diseases or mistreatment. The solution must be applied to the scalp two times a day for four to six months before it does much of anything.

Peak hair growth is seen after about a year and the drug must be used forever or the hair will thin out again, Terezakis said.

Dr. Lorna Thomas, a Detroit dermatologist who spoke at a Pharmacia & Upjohn news conference Wednesday, said many patients are are so distressed by hair loss that they're satisfied that Rogaine as least stops it.

``They say maybe I won't have the same head of hair as when I was 17, but at least it's stable.''