US and Canadian regulators said on Friday they had warned more than 40 Web site operators to stop making unproven claims about preventing or treating SARS with items such as air purifiers and herbal supplements.
"Our message to consumers is, `Hold on to your money.' No products have been found effective in preventing, treating or curing SARS," said Howard Beales, the consumer protection chief of the US Federal Trade Commission.
The regulators said they would go to court and seek orders to shut down any company that continued to make the claims.
SARS, or severe acute respiratory syndrome, is a flu-like virus that has killed hundreds of people and infected thousands, mostly in China and Hong Kong. The outbreak started in southern China and was spread around the world by air travelers.
Beales said some Internet companies were taking advantage of fears about SARS to promote a long list of herbal supplements. Many have been saying that the products can help treat or prevent SARS by boosting the immune system.
Joining in the warnings were the US Food and Drug Administration (FDA) and Ontario's Consumer and Business Services Ministry.
"At a time when people feel vulnerable, scam artists may come forward to prey on people's fears," said Rob Dowling, director of the Ontario ministry.
Mark McClellan, the FDA's commissioner, said the best way to avoid SARS was to take basic hygiene precaution.
Among the Web sites that provoked warning letters from the FDA was www.intensivenutrition.com. According to the letter, it asked the question, "Worried about SARS?" as part of a promotion of a package of supplements to boost the immune system.
Olivia Balogh, a spokeswoman for the operator of that Web site, said the company never intended to suggest that its product would treat or prevent SARS and had already removed the reference from its site.