or weeks, Dr. Guy S. Mayer and his associates have been telling anxious patients cramming into their office in Park Slope, Brooklyn, that they cannot prescribe the antibiotic Cipro because the patients do not have anthrax or are not at risk for exposure.

Now Dr. Mayer has a new problem: Young, healthy patients seeking the influenza vaccine at the urging of city officials trying to control the anthrax crisis are flooding his telephone lines requesting flu shots that are already in short supply.

Last week, Mayor Rudolph W. Giuliani urged all New Yorkers to get a flu shot, saying that because the symptoms of influenza and inhalation anthrax are similar, vaccines might reduce the number of people who go rushing to hospitals mistakenly thinking they have anthrax.

While city health officials said that they recommend the shots should go first to people over 65 or those with chronic diseases, New Yorkers seem to be listening to the mayor. And the demand is far outpacing the current supply, according to doctors and other medical professionals.

"We ran out," said an assistant to Dr. Ian J. Lustbader, who has a practice on East 35th Street in Manhattan. "We're telling people to try back in a week to 10 days."

Faced with a limited supply of the vaccine in New York City at this point in the season, doctors with the vaccine on hand say they have to preserve the doses for the elderly and the physically vulnerable. Others are turning people away because they have no vaccine.

While federal and city health officials acknowledge there may be a delay in the delivery of the vaccine from manufacturers, they said they did not expect an actual shortage of the vaccine, as occurred last year. More doses are being produced this year. But many doctors say the doses are arriving slowly or in small amounts — if at all — and hospitals are not expected to get new shipments until the end of this month.

Dr. Mayer, who said he typically does not recommend flu shots for healthy people under 50, said he had refrained from giving shots to six patients in the last few days who were young and healthy and who said they were acting on the mayor's advice. "I don't think I've ever disagreed with the mayor on anything," he said. "But I disagree with him on this."

Lulu Gore, a nurse at a hospital clinic in Astoria, Queens, said dozens of people had called for appointments or gone to the clinic seeking flu shots in the last week. "I keep ordering it," she said of the vaccine. "And it doesn't come."

Rachel Bader, who lives in Brooklyn, is 35 and has no health problems, called her doctor's office yesterday about getting a flu shot. "She said that unless I was in a high-risk health group, I wasn't going to get the shot," Ms. Bader said. "She said the supply — not just in the office but all over the city — is really, really low."

The American Lung Association began a citywide flu vaccine campaign yesterday, with the first batch of shots given out at a community center in Kew Gardens, Queens. Organizers there said the turnout was higher than expected, although most of the people waiting for shots were age 50 and older or had health problems that would make them susceptible to the flu.

Several, however, said they had tried to receive flu shots from their doctors and were told they had no vaccine, so they attended the Queens event, which required preregistration and was limited to the elderly and other high-risk people. There was enough vaccine for all 200 people who registered, organizers said.

Robert J. Lobdell, first vice president of the American Lung Association of Queens,said it was too early to tell whether people seeking flu shots in an effort to rule out anthrax would overwhelm the two-month campaign. However, he added, "It might complicate things."

Doctors said they were concerned that if someone who received the flu vaccine — which does not protect against other illnesses, like bronchitis, that may feel like the flu — later came down with a fever and muscle aches, they might panic and think they have anthrax.

Linda Goldsmith, who took her elderly parents to the Kew Gardens Center yesterday for flu shots because their Long Island doctor had no vaccine, said she shared the concern. "People have to remember that if they get the flu shot and they get sick, that doesn't mean they've been poisoned by anthrax."