An entertaining fiction is no substitute for real medical treatment.

LET me be as clear as a vial of expensive water: homeopathy is not medicine. This was the recent conclusion of a British House of Commons committee, which found that homeopathy's basic ideas are unconvincing and its claims ''scientifically implausible''. For this reason, our own National Medical Health and Research Council has drafted a statement questioning the homeopathy industry. In response, the Australian Medical Association president suggested that insurers, currently providing rebates for homeopathic treatment, might now think twice.

Given that homeopathy works no better than a placebo, it is certainly reasonable for Australia's medical authorities to crack down on it.

If it seems ridiculous to treat itchy eyes with onion powder, for example, this is because it is ridiculous. As any cook knows, onions can cause stinging eyes, runny nose, brief congestion. For homoeopaths, who believe ''like cures like'', onions are therefore perfect to treat these ailments. They do not prescribe a whole onion or onion powder. Instead, they provide customers with solutions of diluted onion - so diluted the onion only remains in the ''memory'' of the liquid.

Put another way, this is not a medicinal tonic, ointment or drug. It is water. Water is certainly healthy, but it is not a ''cure'' in any way: not from Lourdes, the baptismal font, or the local homoeopath. It is legally questionable and morally dubious to flog it as a remedy for anything but thirst.