For decades now, celebrity athletes and rock stars have been jabbing themselves with vitamin B-12 shots in a quest to elevate their game. While the science behind the practice has never exactly been sturdy, satisfied patients from Mick Jagger to Roger Clemens have reportedly used shots of this common vitamin to boost energy, speed recovery after workouts, improve mental focus, and bolster the immune system. In sports circles B-12 has become a signature of the professional locker room; it was even dragged into last year's steroid scandal, when onetime Oriole first baseman Rafael Palmeiro tried to blame his positive steroid results on the B-12 shot he'd received from teammate Miguel Tejada. (Not that anyone bought it.)

But now B-12 is poised for a different role: the no-strings-attached breakthrough allergy treatment we've long been waiting for. In a Phase III drug trial last fall, a group of seasonal allergy sufferers spent up to six weeks taking massive amounts of B-12 -- 2,500 times the recommended daily allowance -- in the form of lozenges dissolved under their tongues twice daily. The results were impressive, to say the least. The most typical symptoms -- sneezing, congestion, and itchy, runny nose -- were half as severe in the B-12 takers as in the placebo group. Dr. Lyndon Mansfield, a Texas allergist who helped plan the study, says, "The effects were comparable to those that got Claritin approved. But the dramatic thing about B-12 is that it's so darn safe." The tired, parched, spacey feeling so common with antihistamine allergy meds? Nada. And as Mansfield points out, it's practically impossible to OD on the stuff. Perhaps most surprising, though, is the longevity of B-12's effects. Previous studies suggest that the allergy-suppressing benefits still run strong for months after the B-12 treatments. Even almighty Claritin doesn't last more than a day or two.

The secret to B-12's allergy-fighting success appears to lie in the vitamin's ability to retune the immune system. Allergies, after all, are immune malfunctions, and increasingly widespread ones at that. They are now twice as common as they were a generation ago, afflicting more than 50 million Americans. Explanations for this surge vary, but one of the problems seems to be connected to the very nature of modern life: Our immune systems don't get the kind of practice fighting off irritants that they got in the days before air filters and antibacterial soap. As a result, a certain type of immune cell, known as an IgE antibody, stays on a constant hair trigger, ready to call out the body's histamine -- the ultimate source of all that allergy misery -- every time it bumps into a pollen grain.

A company named Cobalis, which funded the Phase III trial, owns a patent on B-12 as an allergy therapy and is seeking FDA approval to start selling lozenges as an over-the-counter allergy medicine. If the company clears the remaining red tape, its product will be on pharmacy shelves by next spring, under the brand name PreHistin. In the meantime, intrepid (or desperate) snifflers can try to replicate the study with their own B-12 fix. Three weeks before the spring pollen starts flying in your area, take six mg of B-12 each day in the form of sublingual lozenges. (The lozenges, available from a variety of leading vitamin brands in one and five mg forms, are a lot easier to track down -- and more comfortable -- than the shots.) Continue the B-12 regimen for a total of six weeks. And if you happen to play a bit more like Tejada when you take the softball diamond this spring, just write it off as a lucky side effect.