The flu, which poses particular dangers to people with compromised immune systems, is distinguished from other bugs by several factors: Its onset is extremely quick, and it brings high fever, cough and sore throat, headaches, extreme fatigue and muscle aches. Although some sufferers, including the elderly and the very young, should seek emergency assistance if the symptoms are extreme, most flu patients will be advised simply to rest, drink fluids and take a fever-reducer such as Tylenol or Advil. "You treat the symptoms," says TIME medical contributor Dr. Ian Smith. "Flu isn't life-threatening it just makes people feel horrible."
As the recent upswing in emergency room visits indicates, this year's flu strain has hit early and often, taking a toll both on patients and exhausted doctors. According to CNN, a spokesman from California's Health and Human Services Department has tried to ease the pressure on beleaguered hospital staff by asking the public not to descend on the state's emergency rooms. After a stint in the Southwest, the flu is bearing down with particular force on the Northeastern states: Public health facilities across New York, New Jersey, Pennsylvania and Virginia are dealing with a massive influx of patients suffering from a Sydney strain of influenza, this year's main culprit; a crop of other, non-flu viruses is also to blame for the crowded ERs.