- What causes the flu (influenza)?
- How dangerous is the flu?
- How long does the flu last, and how can I shorten it?
What causes the flu (influenza)?
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.
How dangerous is the flu?
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.
How long does the flu last, and how can I shorten it?
If you get the flu, there are treatments that can reduce both the intensity and duration of your suffering:
- Over-the-counter medications such as pain relievers, decongestants, and antihistamines can reduce the severity of your symptoms, but these are not treatments for the viral infection itself. There are over-the-counter flu preparations available that combine these types of medications. (Remember that aspirin should not be given to those under 18 years of age because of its association with Reye syndrome, a serious condition that affects the nervous system and the liver.)
- Lifestyle measures such as bed rest, drinking plenty of fluids, and proper nutrition can also help reduce the severity of your illness. Restrict your activity levels until the symptoms have disappeared.
- Finally, your doctor may recommend antiviral medications. Certain medications are effective in reducing the severity of the flu if taken within two days after symptoms develop. These drugs treat the viral infection itself. Four antiviral medications are available to treat an infection with the flu virus:
If you develop symptoms of the flu, contact your health care practitioner early so that he or she can decide if any of the antiviral medications are necessary for you. For antiviral medications to work effectively, it is important to start treatment as soon as possible after symptoms develop.
Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine
American Lung Association Web site "Influenza" and "Cold and Flu Guidelines: Influenza," 2008.