The government warned doctors yesterday to make sure they appropriately prescribe those heavily advertised--but only somewhat helpful--new flu drugs, Relenza and Tamiflu.

The Food and Drug Administration is looking into a handful of reports of patients who were possibly treated inappropriately.

The warning also comes because the nation is in what health officials say appears to be a normal influenza epidemic--lots of misery but so far no worse than any year's epidemic--yet influenza is getting tremendous media attention. In addition, Relenza and Tamiflu are being promoted heavily because they are new to the market.

"We want to make certain that physicians aren't thinking of these drugs before they would think to use antibiotics" or other medicines, said FDA antiviral chief Heidi Jolson.

The FDA's first warning: Flu drugs do not prevent people from catching influenza. Vaccination is the best way to do that.

It is not too late to be vaccinated, although some regions may start running low on vaccine, said Keiji Fukuda of the Centers for Disease Control and Prevention. He advised people at highest risk--the elderly and people with chronic heart or lung conditions such as asthma--to ask their doctor about vaccination.

When doctors do prescribe the new flu drugs, the FDA warned:

* Patients with severe flu-like symptoms, especially those with chronic medical conditions, may have serious bacterial infections like pneumonia instead of influenza. Neither the new Relenza and Tamiflu, nor two older flu medicines, can help bacterial pneumonia. Those patients need antibiotics.

The FDA has received reports of three people who died from bacterial infections who at least initially may have been given flu drugs instead of antibiotics, Jolson said.

* The flu drugs only work if taken within the first 48 hours of flu symptoms--and they then reduce flu symptoms only by about a day.

"If they are used, it should be with a realistic expectation of the likely benefit from the drugs, which I would characterize as modest," Jolson said.

* Use special caution in prescribing Relenza, which is an inhaled drug, to patients with underlying asthma or other lung disease because it might trigger asthma attacks or wheezing. Although Relenza comes with a warning about that side effect, the FDA has received four reports of asthma attacks in such patients, a small number but one that signaled doctors needed a reminder, Jolson said.

Also yesterday, the FDA revealed that in November it had ordered Relenza manufacturer Glaxo Wellcome to stop airing misleading television ads implying the drug is more effective than it really is.