Flu and anthrax symptoms are startlingly similar, and in light of the anthrax scare, people who would normally suck it up are scrambling to emergency rooms and doctors' offices for fear that their fevers and aches could mean they are victims of bioterrorism.

The flu season runs from November through April, with the heaviest toll coming around February. But doctors report that they are already feeling overwhelmed by worried patients.

"I have over 100,000 doctors of internal medicine in the American College," said Dr. William Hall, president of the American College of Physicians, the nation's largest medical specialty society. "I can tell you they are being inundated with calls and office visits of legitimately concerned people wondering about their own health and their children's health."

Dr. Jo Ann Pullen, an internist at St. Vincent's Medical Center in Los Angeles, said she was already seeing a full load of patients every day. Now she's bracing for an overload. 

"It's scary," she said. "The influenza season is coming ... and it's going to be very difficult for physicians and patients to differentiate between influenza and anthrax. We've seen it already ... people have come in with little allergies or common colds."

Dr. Richard Paley, associate chief of emergency medicine at North Broward Medical Center in Pompano Beach, Fla., works mere minutes from the site of the first anthrax death.

"Our biggest rush of patients concerned with anthrax was in the few days and weeks after the first reported cases down here," Paley said. "We had two peaks — after the initial reports of inhalation anthrax, when we started seeing people with respiratory problems, coughs, malaise. Then again when cutaneous anthrax was reported in New York, when people came in with rashes, hives, chicken pox or just itchy skin.

"I suspect that once the flu season gets going it could be potentially worse," Paley said. "It depends on the social setting, how high the public's anxiety is at that point ... if it's high when the season hits it could be very difficult for emergency departments across the country to deal with."

Dr. Gabe Kelen, professor and chair of emergency medicine at Johns Hopkins Hospital in Baltimore, is also concerned with the emergency department's ability to handle a flood of these cases. “The current system of care is going to become overwhelmed as patients who wouldn’t usually go to the emergency department or their doctor's office will be coming in concerned that what they have isn’t just the flu," he said.

Kelen explained that most medical professionals have had little experience treating anthrax, and "differentiating the two can be a little tricky. Most people who have flu slowly get better, but if you have anthrax or plague your condition rapidly deteriorates. A type of follow-up will be absolutely key."

Dr. Timothy Flaherty, chair of the American Medical Association said, “I think in areas where this has been a specific concern, Florida, D.C., New York, there is a higher concern. The ERs in this country have really been overtaxed, that’s been an issue for the past year or so, but ERs won’t turn people away.”

Doctors across the country are advising patients to get their flu shot and help eliminate diagnosis confusion by preventing the symptoms from ever developing. October and November are the optimal months to receive the vaccine.

"I think we will have a very high compliance rate with flu shots this year," Dr. Flaherty said.

Early symptoms of the two ailments can help distinguish anthrax from the flu.

According to the Centers for Disease Control, each type of anthrax has it's own warning signs. Inhalation anthrax has initial symptoms much like a cold or flu, but progresses to severe breathing problems and shock anywhere from several hours to several days later.

Cutaneous anthrax victims develop a skin infection that begins as a raised itchy bump similar to an insect bite. Within one to two days it develops into a sore, then into a painless ulcer with a black center. Lymph glands in the adjacent areas also may swell.

Intestinal anthrax initially begins with nausea and loss of appetite. The vomiting and fever are followed by abdominal pain, vomiting of blood and severe diarrhea.

The flu, also known as influenza, is a virus typically spread when an infected person coughs or sneezes into the air. Fever, dry cough, sore throat, runny or stuffy nose, headache, muscle aches and severe fatigue are all features of the flu.

According to the CDC, influenza is the major cause of illness and death in the U.S. and leads to approximately 20,000 deaths and 110,000 hospitalizations each year.

If you develop flu-like symptoms or fear you have warning signs related to anthrax, don't panic. Doctors say the best thing to do is to make an appointment with a physician and trust in their advice.

Fox News' Jon Du Pre contributed to this report.