Everything You Need to Know About the Flu

Medically Reviewed by Madeline Hubbard, RN, BSN

Photo Courtesy: [Brothers91/E+/Getty Images]

“The flu” is a term commonly used to describe seasonal influenza, an illness caused by one of numerous influenza viruses. This highly contagious infection affects your respiratory system, causing symptoms that can range from mild to life-threatening.

The Centers for Disease Control and Prevention (CDC) estimates that 3–11% of the population within the United States becomes infected with the flu each year. Among infected individuals, hundreds of thousands may require hospitalization and more than 36,000 individuals typically die each year from the flu. Infections are most common in the fall and winter, so this period of each year is referred to as “flu season.” If you’re concerned about the flu, learn more about the symptoms to look out for, along with some important tips for stopping the spread of this serious illness.

Causes of Influenza

There are several types of influenza viruses that can cause infection. Each of these viruses is spread from person to person via droplets that are naturally expelled when we talk, cough, sing or sneeze. Other people can then inhale the droplets or transfer them into their bodies by touching a contaminated surface and then touching their eyes, nose or mouth. Once the virus enters your body, it quickly replicates and causes symptoms of the flu.

A person who’s infected with an influenza virus is typically contagious one day before their symptoms begin appearing and up to seven days after their symptoms first start. During this period, the virus is actively replicating and can easily be passed on to other people who are in close contact.

Symptoms of Influenza

Symptoms of the flu usually begin within one to four days of exposure to the virus. Many common flu symptoms are very similar to cold symptoms, though they typically come on more suddenly than they do when you have a cold. When you’ve been infected with an influenza virus, you’ll likely experience some or all of the following:

  • Fever
  • Coughing
  • Sore throat
  • Runny nose
  • Congestion
  • Headaches
  • Body or muscle aches
  • Chills
  • Fatigue or weakness
  • Loss of appetite
  • Nausea, vomiting or diarrhea (these occur more often in children)

Generally speaking, flu symptoms are more severe and more debilitating than symptoms of the common cold. Flu symptoms typically last for one to two weeks and most often resolve on their own. However, in certain cases, influenza infections can lead to more serious complications and require intervention from a medical professional.

Certain populations are at a higher risk of developing health complications related to the seasonal flu. These individuals include:

  • Children under 5 years old (children under 6 months have an even greater risk)
  • Adults 65 years of age or older (especially in long-term care environments)
  • Pregnant people or those who have recently given birth

People living with the following health conditions also may be at a higher risk for developing complications from the flu:

  • Chronic lung disease or asthma
  • Heart disease
  • Blood, kidney or liver disorders
  • Metabolic disorders
  • Neurological and neurodevelopmental conditions
  • Obesity
  • Individuals under the age of 19 who are taking long-term aspirin therapy
  • Anyone with a compromised immune system, like people living with cancer, HIV or AIDS

If you experience flu-related complications, you may need to be hospitalized to receive effective care. Flu-related complications include:

  • Pneumonia
  • Bronchitis or severe asthma
  • Heart problems
  • Ear infections
  • Death

Diagnosing Influenza

Often, when influenza symptoms are mild and occur during flu season, your healthcare provider may make a diagnosis based on your medical history and symptom report alone. It’s also possible to directly test for the presence of the influenza virus via a respiratory swab. Your doctor may collect a sample of fluid from your nasal passage, and this sample will be tested to determine whether you have the virus. The physician may order blood tests or X-rays if the severity of the infection indicates you may experience possible complications.

If you fit into any of the above categories that have a higher risk for developing dangerous complications from influenza, it’s important to contact a healthcare provider right away when you develop symptoms. If you experience any difficulty breathing, dizziness or chest pain, contact emergency services by dialing 911 immediately.

Treatment for Influenza

Unless you’re at risk of developing flu-related complications, you can likely treat seasonal influenza at home under your doctor’s guidance. Recommendations include:

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  • Drinking plenty of fluids and maintaining a healthy nutritional intake
  • Getting adequate rest
  • Using over-the-counter pain and fever relief medications
  • Avoiding close contact with others as much as possible until your fever has been gone for at least 24 hours without medication

If you’re at a higher risk of developing complications or if your symptoms increase in severity, your doctor may be able to give you certain antiviral medications to treat the flu. These medications are meant to shorten the duration of an infection.

Because of the highly contagious nature of influenza, and its annual prevalence, it’s very important to take precautions to help prevent the spread of this illness. Keep the following tips in mind, especially during flu season each year:

  • Wash your hands frequently, especially after touching high-contact surfaces
  • Avoid touching your eyes, nose and mouth
  • Keep surfaces around your home and workspace clean and disinfected
  • Be mindful of crowds and avoid them whenever possible
  • Maintain distance from anyone who’s ill or known to be infected
  • Get a flu shot every year

Vaccinations, or flu shots, are available every year and are specifically developed to target the strains of influenza that are most likely to be dominant that year. The CDC recommends that every person over the age of 6 months receive a flu shot each year to effectively protect against influenza infection and its possible serious consequences.

Vaccinations can take the form of an intramuscular injection or a nasal spray, and they work by causing your body to develop antibodies that can then recognize and fight off the influenza virus if you come into contact with it in the future. Flu vaccinations do not cause illness, and they’re an effective tool for preventing the effects of influenza in individuals and communities. Talk with your healthcare provider about the appropriate type and timing of vaccination for you.

Resource Links:

https://www.cdc.gov/flu/about/keyfacts.htm

https://www.niaid.nih.gov/diseases-conditions/influenza

https://www.ors.od.nih.gov/flu/pages/default.aspx

https://www.mayoclinic.org/diseases-conditions/flu/symptoms-causes/syc-20351719

https://www.cdc.gov/flu/prevent/keyfacts.htm