What to Do if You Get the Flu

Medical Author: Melissa Conrad Stoppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Influenza, or the "flu," is an illness of the breathing system (respiratory system) and muscles caused by a virus. While a vaccine is available to prevent the flu, its effectiveness varies according to the degree of match between the viral strains used to prepare the vaccine and those strains actually in circulation in a given year. Not everyone receives the flu vaccine, and even some of those who do can develop symptoms of the flu.

Mild cases of the flu may seem like common colds. But most cases of the flu can be distinguished from colds because the symptoms (cough, muscle aches and pains, sore throat, fatigue, and headache) are more severe than those of the common cold. Flu symptoms also tend to occur suddenly and include high fevers (temperatures of 101 F or more [37.7 C]). In children, fevers are typically even higher than those in adults.

The flu is a serious illness that can be fatal in people whose immune systems are weakened, the elderly, and those with chronic medical conditions. Each year 30,000-35,000 people die in the U.S. from the flu or its complications. Even healthy people who develop the flu cannot work, attend school, or participate in normal activities for several days. Complications of the flu can develop in anyone and include pneumonia, ear infections, sinus infections, or bronchitis. These bacterial infections can develop as a complication of the flu because the body's immune system is weakened from the illness.