Influenza is a respiratory infection caused by flu viruses that travel through the air and enter the body through the nose or mouth. Five to 20 percent of Americans get the flu each year, and anyone is susceptible to the virus. During the 2017-2018 flu season, approximately 900,000 people were hospitalized and 80,000 people died due to flu complications, according to the Centers for Disease Control and Prevention.
Flu symptoms range from mild to severe and can include fever, chills, achy muscles, sore throat, cough, and headache. The flu is often confused with the common cold, but flu symptoms develop more suddenly.
What causes the flu?
When someone with the flu coughs or sneezes, droplets carrying the virus enter the air. You can catch the flu if you inhale these droplets through your nose or mouth, or if you touch objects such as doorknobs or keyboards that are contaminated with the virus and then touch your nose, eyes, or mouth.
Flu risk factors
Flu viruses are constantly changing, so if you’ve had influenza in the past, you may come down with it again. You are at greater risk of catching the flu and developing complications if you:
- are younger than 4
- are older than 65
- live in a nursing home or long-term care facility
- are pregnant or up to two weeks postpartum
- have a weakened immune system
- have a chronic illness
- have a body mass index of 40 or higher
What are the symptoms of the flu?
Symptoms of influenza are often similar to those of a common cold, but appear suddenly and are more severe. Symptoms include:
- Achy muscles, especially in your back, arms, and legs
- Stuffy nose
- Sore throat
- Chills and sweats
If it is flu season and you are generally healthy and experience symptoms, you don’t need to see a doctor, says Joseph Ladapo, MD, PhD, professor of medicine at UCLA. Simply treat your symptoms with rest and over-the-counter medications. However, anyone who is at high risk—that is, a child, older adult, pregnant woman, or someone with a chronic condition such as diabetes, heart disease, or stroke—see your doctor. “He or she can follow up with you to confirm that things are going in the right direction,” Dr. Ladapo says, or advise on seeking more care if they feel it’s necessary.
Cold vs. flu
How is the flu diagnosed?
The most common test is the rapid influenza diagnostics test. Your doctor will swab the back of your nose or throat and check the sample for antigens, substances that cause your immune system to produce antibodies. It takes less than a half hour to get results. However, results aren’t always accurate, so your doctor may diagnose the flu without this test. “Trust your doctor and listen to your body,” Dr. Ladapo says.
Some specialized labs and hospitals use more accurate tests that look at the DNA or RNA of the virus.
If you decide to see your health care provider, be ready to answer questions about your symptoms, how long you’ve had them, and how severe they are. Also let them know of any medical conditions, if you are pregnant, and if you live with anyone at high risk of influenza complications, Dr. Ladapo says.
How is the flu treated?
If you promptly see your doctor upon noticing symptoms, he or she may give you an antiviral such as oseltamivir (Tamiflu) or zanamivir (Relenza). Tamiflu comes in capsule form, while Relenza is a powder you inhale. If taken within two days of the onset of symptoms, these can lessen symptoms and shorten the length of time you are sick by about a day.
However, “it’s far from a slam dunk,” Dr. Ladapo says. “By the time you can schedule a doctor’s appointment, you may be outside the window where it’s effective.”
Whether or not you take an antiviral, the best way to treat the flu is to rest, drink fluids, and use any other remedies that best alleviate your symptoms such as pain reliever for headaches and achy muscles. “Whatever you are used to and know works for you, that is the appropriate treatment for flu,” says Michael P. Angarone, DO, professor of infectious diseases at Northwestern Memorial Hospital.
Flu complications to know
Healthy people typically recover from the flu once the virus passes. However, those at high risk of complications may develop complications, which can be deadly. These include:
- Sinus and ear infections
- Asthma flare-ups
- Inflammation of the heart, brain, or muscle tissues
- Multi-organ failure
- Sepsis, a life-threatening response to infection
- Worsening of conditions such as heart disease
If you have a health condition and come down with the flu, talk to your doctor, who can help monitor your symptoms. If you have the flu and the fever persists for more than a few days or you experience difficulty breathing, chest pain, persistent cough, lots of sputum (mucus), or feel weak or lightheaded, seek medical attention immediately. “These are signs the virus is not getting better or you may be developing a complication,” Dr. Angarone explains.
How to prevent the flu
You can reduce your risk of contracting influenza with some common-sense health practices.
Experts widely agree that the single best way to protect against the flu is getting the flu vaccine each year. The vaccine is appropriate for anyone 6 months and older, and it’s important to get the vaccine each year. The injection protects against the three or four flu viruses that research indicates will be most common that year. You can get the flu vaccine at your health care provider’s office or at many pharmacies.
And despite what you may have heard, the vaccine cannot give you the flu. “It is true that the vaccine can lead to flu-like symptoms when the body responds to the proteins in the vaccine. But even then, it’s still protective, and those symptoms are not as severe as the flu,” Dr. Ladapo says.
In addition to the vaccine, practicing good hygiene can prevent flu germs from spreading:
- Wash your hands. Use soap and water, scrubbing for at least 20 seconds (or as long as the Happy Birthday song). When soap isn’t available, use alcohol-based hand sanitizer.
- Cough or sneeze into a tissue and discard the tissue. If you don’t have a tissue, cough or sneeze into your elbow.
- Avoid crowded areas. The flu spreads more easily in heavily trafficked places such as public transportation, schools, and offices. If you are sick, stay home for at least 24 hours after any fever subsides.
- Avoid touching your eyes, nose, and mouth to avoid germs entering your body.
- Clean and disinfect surfaces and objects such as keyboards, doorknobs, and telephones that may be contaminated with germs.