The flu is caused by a virus. There are many different strains of flu virus. The strains often change from year to year. The flu virus may be spread by:
- An infected person sneezes or coughs and those nearby breathe in droplets that were released
- Touching surfaces contaminated with the virus, then touching the mouth or nose
Things that raise the risk of getting the flu are:
- Living or working in crowded areas—such as nursing homes, schools, daycare centers, and the military
- Being physically or mentally disabled
Some people have a higher risk for severe flu, or problems from the flu. This includes children less than 5 years old and adults over 50 years old. Other things that raise the risk are:
Certain health conditions, such as:
- Diseases of the heart, kidneys, liver, blood, or nervous system
- A weak immune system
- Living in long-term care facilities
- Being American Indian or Alaska Native
Symptoms usually start quickly. They may be:
- High fever and chills
- Headache and severe muscle aches
- Severe tiredness
- Lack of hunger, or nausea, vomiting, and diarrhea
- Cough, sneezing, and runny or stuffy nose
- Watery eyes, or red eyes from conjunctivitis
- Sore throat
- Swollen lumps (lymph nodes) in the neck
Most can clear the virus on their own. Treatment can help to ease symptoms. The flu usually lasts 7 to 10 days. A cough or tiredness may last longer. People with severe symptoms or problems may be treated in the hospital.
Treatment options are:
- Home care—such as rest and drinking plenty of fluids
- Symptom treatment with over-the-counter medicine, such as:
- Acetaminophen or ibuprofen—to reduce pain and fever
- Cough remedies
- Decongestants—to ease stuffiness
- Antihistamines— to ease a runny nose, or itchy and watery eyes
- Antiviral medicines—for severe symptoms or people at risk for them
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
Copyright © EBSCO Information Services
All rights reserved.
Centers for Disease Control and Prevention https://www.cdc.gov
World Health Organization http://www.who.int
Public Health Agency of Canada https://www.canada.ca
The College of Family Physicians of Canada http://www.cfpc.ca
Gaitonde DY, Moore FC, et al. Influenza: diagnosis and treatment. Am Fam Physician. 2019;100(12):751-758.
Inactivated influenza VIS. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html. Accessed January 29, 2021.
Influenza. American Lung Association website. Available at: http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/influenza. Accessed January 29, 2021.
Influenza in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/influenza-in-adults. Accessed January 29, 2021.
Influenza in children. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/influenza-in-children . Accessed January 29, 2021.
Key facts about seasonal influenza (flu). Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/flu/keyfacts.htm. Accessed January 29, 2021.
Seasonal influenza vaccination. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/seasonal-influenza-vaccination. Accessed on February 24, 2021.
What you should know about flu antiviral drugs. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/flu/antivirals/whatyoushould.htm. Accessed January 29, 2021.