BEIJING -- Doctors at a Shanghai hospital have concoted what they claim is an herbal "sober-up" tonic that works wonders on hangovers and is even said to prevent imbibers from getting drunk.

The tonic is made with Chinese herbs and looks and tastes "a little bit like Coca-Cola," said Chen Lianfang, deputy director of Shuguang Hospital's scientific research office.

She and other researchers declined to disclose the ingredients of the drink, and said they themselves are not sure how the tonic works.

To be sure, China has a long record of alleged wonder cures for diseases from AIDS to heart disease that have proved to have no medicinal value. For example, Chinese pharmacies market something called the "Anti-AIDS Foam Bath," which is supposed to take three minutes to "inactivate" AIDS.

According to a recent article in the official China Daily newspaper which quoted doctors at the Shanghai hospital, the hangover tonic "can relieve internal heat or fever, invigorate the function of the spleen and is good for the stomach." It is also supposed to reduce dizziness and nausea after drinking, all without harmful side effects.

The hospital is working with researchers from Hua Yuan Drying Technology and Engineering Corp., which helped fund the product. Initial tests have been conducted on 100 individuals who have imbibed alcohol in varying amounts. "The drink proved 100 percent effective," she said.

In some cases, the tonic prevented individuals from becoming drunk despite ingesting large amounts of alcohol. Tests showed that shortly after taking the drink, the individual's blood alcohol content dropped. In other cases, those individuals who drank the tonic before consuming spirits were able to drink much more than usual, she said. The tonic, however, has little effect on serious cases of alcohol poisoning, she said.

Chen said interest in developing such a drink was prompted by the rise in cases of intoxication in China. Social drinking here has increased as economic reforms have brought higher incomes.

Cai Gang, hospital vice president and one of the researchers, said work on the drink began last year, and the hospital is looking for a factory that will be able to produce the drink. The goal is to sell the drink on the domestic market by summer and eventually make it available in foreign countries.

A 200-cc bottle of the as-yet-unnamed tonic will cost the average Chinese about 15 cents, he said. The idea is to market the drink not as a medicine but as a beverage to be served with alcohol.

Cai acknowledged that development of such a tonic may "encourage people to drink more. But that is not our original intention."