In the , the off-label use of drugs wasn't openly discussed until April 1982, when the US Food and Drug Administration (FDA) changed its regulations to allow physicians to prescribe drugs for uses that were not included in the approved labeling. Prior to that time, the FDA's position was that drugs were approved for only specific uses, and it was illegal to order a drug for any use but the ones listed in the official labeling.

But the new rules also had problems. While the labeled uses were approved by panels of experts, who carefully reviewed detailed studies, the unlabeled uses were based on pretty much anything that appeared in the medical literature – even on anecdotal reports that turned up in the Letters to the Editor section of throwaway journals.

The all-time record for drugs with the most unlabeled uses (at least drugs produced by a pharmaceutical company) should probably go to phenytoin. Marketed as Dilantin, this drug was internationally approved for treatment of grand mal convulsions. But in the early 1960s, the Wall Street billionaire Jack Dreyfus, founder of the Dreyfus Fund, "discovered" phenytoin as a cure for his depression. After having the drug researched, he was so impressed that he wrote a book: A Remarkable Medicine is Being Overlooked. This book, part autobiography part bibliography, offers 50 different uses for phenytoin, including for the treatment of anal itching and reduction of bedwetting. Even the authoritative Martindale's Extra Pharmacopoeia credits phenytoin with value in hiccups, skin diseases, rheumatoid arthritis, and even binge eating.

Carbamazepine (sold as Tegretol in North America) has become so widely used that one wag commented: "if you go to a pediatrician, you get a lollipop; go to a neurologist, you get Tegretol." Officially, it's for use only in some types of epilepsy and in trigeminal neuralgia (also called tic douloureux, which can cause severe facial pains.)

But the list of unapproved uses includes treatment of some of the symptoms of beriberi (yes, you're right, beriberi is a thiamine deficiency, but it causes pain that can be treated with carbamazepine) diabetes insipidus, multiple sclerosis, and a wide range of psychiatric conditions including bipolar disorder, intermittent explosive disorder, panic disorder, schizophrenia, alcohol withdrawal, and some of the agitation associated with Alzheimer's disease.

Then there is vitamin C (ascorbic acid). The claimed benefits of this drug started with a two books by Dr. Linus Pauling: Vitamin C and the Common Cold and Cancer and Vitamin C. Pauling, who won two Nobel Prizes (one for chemistry in 1954 and one for peace in 1962), gave a particularly intelligent discussion of how vitamin C, in doses far larger than those used to treat vitamin deficiency, might prevent, or even cure, the common cold.

But other writers got hold of the idea and started making new claims for vitamin C. A partial list includes, asthma, atherosclerosis, infections, infertility, and bone disorders. This vitamin has also been tried as a treatment for pain, drug addiction, HIV, and AIDS. Applied to the skin (it's claimed), vitamin C can reduce wrinkles, lighten freckles, and offer some protection against skin damage from the sun. So far, there is no strong evidence that vitamin C is useful for anything except treating a vitamin C deficiency.

Vitamin E (tocopherols acetate) has an even larger number of unlabeled uses than Vitamin C. Because it was found to be essential for reproduction in rats, vitamin E has a totally unjustified reputation as a sex stimulant. At the same time, it has been used in the treatment of anemias and eye problems in premature babies. And the Cambridge Heart Antioxidant Study (CHAOS) reported that 400 to 800 units of vitamin E daily reduced the frequency of non-fatal heart attacks.

Vitamin E has also been recommended for treatment of burns and hemorrhoids. It has been used to treat Parkinson's Disease, Alzheimer's disease, and tardive dyskinesia, a serious adverse effect of some major tranquilizers. Finally, vitamin E, like vitamin C, is a potent antioxidant and so has been recommended for life extension and maintaining youth.

What single drug has the most unlabeled uses? If you want a rigid definition – a product listed in pharmacopoeias – then Dreyfus's money buys the winner: phenytoin.

But, does "drug" mean only those items marketed by pharmaceutical manufacturers, or does it include botanicals and herbs?

The Encarta dictionary gives this definition of drug: a natural or artificial substance that is given to treat, prevent, or diagnose a disease or to lessen pain. If you use that definition, then the greatest cure-all of all time, better than ginseng, sarsaparilla, and Old Dr. Kaufmann's Great Sulphur Bitters, is thriving in the western United States. It's a material called Catalyst Altered Water or Willard Water, in honor of the man who formulated it, Professor John Willard of the South Dakota School of Mines and Technology, in . In 1970, Willard was looking for a solution that would help clean mineral samples. What he found was, according to its advocates, the greatest all-purpose remedy since sacrificing a calf to Asclepius.

According to one ad for Willard Water: "There have been reports of beneficial results from people with all the following conditions: arthritis, emphysema, digestive problems, migraines, back pain, diabetes, skin problems, burns stomach ulcers, and high blood pressure. Willard Water is also used to calm aggressive animals. In addition, cattle, quail, chickens and other animals that are given Willard Water to drink are plumper and more healthy."

The American Cancer Society, in its guide to Complementary and Alternative Therapies writes: "Proponents claim that Willard Water eases the burning caused by radiation therapy, relieves sores in the mouth and on the lips, eliminates bad breath, removes plaque from teeth, heals minor skin irritations prevents hangovers, and eases pain from arthritis and muscle sprains. They also claim it flushes toxins from the body and eliminates harmful free radical molecules."

However, the American Cancer Society cautions: "Since no scientific studies have been conducted on Willard Water, there is no evidence to support these claims. It has not been proven useful for any medical condition and the exact contents are not known. Not enough is known about Willard Water to know whether it is safe."

Barring that, there's not much that Willard Water won't do. Spray it on a tooth, and your dentist can drill without causing pain. Spray it on your African violets and they'll bloom with more color than ever before. Use the wonder water when you wash dishes and they'll come out cleaner. The uses of Willard Water are limited only by imagination – but none of them have been approved by any review panel. All the claims seem to be based on testimonials and anecdotal reports.

So, for centuries, scientists and alchemists have been searching for the philosophers' stone, a material that, at first, could transmute base metals into gold, but later was thought of as a material that could restore life and health. But, when the long sought substance is found, it turns out to be not a miracle of arcane, but a tub of dirty dishwater.