This leads to a certain amount of confusion. Many people tend to think of homeopathic products as herbal remedies when, in fact, they contain little if any of the desired herb. According to homeopathic practitioners, the solutions do continue to hold a "trace memory" of the original substance. Mainstream scientists, however, find them completely devoid of any meaningful amount of medicine.

What, then, can homeopathic remedies do for you? As far as science can determine, the answer is Nothing. On the other hand, advocates of this therapy say that clinical research has shown certain homeopathic medicines to be more effective than a placebo (dummy pill) in the treatment of seasonal allergies, asthma, and influenza. Proponents also claim verified benefits for a variety of other conditions, from easing labor and childbirth to speeding the healing of a sprained ankle. Still, these claims have yet to be confirmed by the kind of broad-based, carefully controlled testing demanded for other types of medication.

There are literally thousands of homeopathic remedies, and their alleged benefits cover just about every disease symptom imaginable. Since they are as safe as bottled water (in fact, often are bottled water), there's no harm in trying them for relief of annoying conditions such as colds, flu, headache, and indigestion. It would be unwise, however, to use them as the sole remedy for any serious medical condition. Not only would you be foregoing the possibility of a speedy cure when faced with an ailment like an infection, you'd also be risking dangerous complications when suffering from progressive conditions like heart disease and cancer.

A homeopathic practitioner (who may be a physician, chiropractor, or unlicensed entrepreneur) typically begins by taking a lengthy medical history, including detailed information on an individual's temperament, preferences in diet and lifestyle, and emotional state. From these findings, a "classical" homeopathic practitioner will build a "symptom picture" against which to match homeopathy's extensive array of remedies. More eclectic (or opportunistic) practitioners may also employ props such as "electrodiagnostic devices" that beep and give read-outs when a probe is pressed to the skin.

Remedies (in the form of alcohol or water solutions or sugar pills) are usually prescribed one at a time, although they may be combined. Homeopathic practitioners may rely solely on homeopathy, or may complement this approach with standard medicine or other alternative therapies such as naturopathy. For instance, a homeopathic physician might try homeopathic remedies to relieve a child's ear infection, turning to antibiotics only if the homeopathic products fail to work a cure.

At the turn of the 19th century, little was known about the causes of disease, so Hahnemann focused on the symptoms instead. Noting that cinchona, a malaria remedy, produced malaria-like symptoms when taken by a healthy volunteer, Hahnemann concluded that "like cures like": A substance that causes certain symptoms should also relieve them. He then proceeded to test a vast number of plant, animal, and mineral substances on himself and others in a procedure called "proving," observing the symptoms they produced and categorizing them as cures for disorders that cause similar troubles.

The idea that like cures like wasn't new; it had been suggested by the ancient Greek physician Hippocrates, among others. But Hahnemann added a twist called the "Law of Infinitesimals." Because large doses of many remedies were quite poisonous, he began to experiment with smaller and smaller amounts, ultimately coming to believe that minute doses were actually more effective. Hence it became a tenet of homeopathy that the more diluted a substance is, the more powerful its healing action will be.

To maximize the effect of his remedies, Hahnemann therefore invented a system for "potentizing" them. Each substance was repeatedly diluted and shaken until, at the "higher" potencies, not one molecule of the original substance remained. For example, a homeopathic remedy labeled "12X" has been diluted by a factor of ten, 12 times in a row, to produce a dilution of 1 part in a trillion.

Since it's impossible for such a solution to have any physical effect, homeopaths ascribe the therapeutic action of their remedies to an "essence," "memory," or "energy imprint" that can mobilize the body's "vital forces." Medical science, on the other hand, attributes any relief either to coincidence (when an illness runs its course) or the placebo effect (the power of suggestion).

Despite the implausibility of homeopathic theories, results of clinical research have not been entirely negative. In 1997, an international team of researchers reviewed over 100 controlled studies that had claimed positive results from homeopathy. The team deemed 26 of these experiments to have been designed and carried out according to the most rigorous standards. By themselves, none of these studies showed homeopathy to be clearly effective. However, when taken as a group, they seemed to indicate that homeopathy produced somewhat greater benefit than placebo.

Noting the lack of any scientific theory to explain the results, the team simply said they showed the need for more intensive research. Some baffled scientists commented that if placebo-controlled clinical trials could show some effectiveness for homeopathy, then the trials themselves must be subject to as-yet-unidentified bias on the part of the researchers. Others simply ascribed the results to luck, noting that if you perform enough trials, a few will deliver positive results merely by chance.

Proponents of homeopathy respond that conventional medicine still uses a variety of drugs that were shown effective by trial and error long before their mechanism of action was understood. Homeopathic practitioners also point to vaccination as an example of "like curing like," and note that smaller doses of certain standard drugs (such as aspirin to prevent heart attack) are more effective than larger doses. To critics, however, these examples are irrelevant. Neither aspirin nor vaccines would have any effect if diluted to the strengths found in homeopathic products. Furthermore, say opponents, homeopathy's emphasis on matching remedies to symptoms, and not to underlying disease states, discards the vast body of discoveries made since the time when Hahnemann proposed his theory.

Unlike vitamins and herbal remedies, which are sold as "dietary supplements," homeopathic remedies are marketed as over-the-counter medications--but with a unique exemption from standard regulatory procedures. In 1938, U.S. Senator Royal Copeland of New York--a leading homeopath--included a special release for homeopathic remedies in the landmark Federal Food, Drug, and Cosmetic Act, allowing them to be sold without proof of safety. Today they continue to be marketed without the evidence of safety and efficacy required of other medications. Their labels must, however, include ingredients, directions, dilution, and at least one indication (what the medication is to be used for).

The vast majority of homeopathic remedies do not require a prescription, so any motivated individual may in effect become an amateur homeopath by consulting reference books and taking remedies available at health food stores, pharmacies, or by mail order. In many states, however, prescribing even non-prescription medications (including homeopathic ones) for other people without a medical license is illegal.

Although homeopathy is often recommended as a "safe and gentle" alternative therapy for children, always keep in mind why it's so safe. If symptoms such as diarrhea, headache, fever, or abdominal pain fail to clear up, see a doctor before the situation gets worse.