National Center for Health Promotion and Disease Prevention
Influenza, or "flu," is a contagious respiratory virus. Flu season usually begins in the fall and can continue through late spring.
Anyone can be infected by the flu virus. Flu can be mild or serious for some and deadly for others. Flu causes hospitalizations and deaths, especially among vulnerable groups such as the very young, people ages 65 and older, and those with chronic medical conditions.
Get a flu shot every year to protect yourself and help keep the flu from spreading to others.
Symptoms of flu
- Fever of 100°F or higher
- Body or muscle aches
- Feeling tired or weak
- Sore throat
- Runny or stuffy nose
- Stomach symptoms, mostly in children
Symptoms can vary in severity from mild to severe. While some people experience mild symptoms, not much different than a cold, others may get a severe infection that requires hospitalization. Know when to seek medical care.
Is it a cold... or the flu?
Although some of symptoms of seasonal flu are the same as a cold, people with colds don't usually have fevers of 100°F or higher, chills, body or muscle aches—all of which are common with the flu.
VA has tools to help you better understand the differences between colds and flu and know when to seek medical care.
- Take VA's easy and useful flu self assessment.
- Download a flu self assessment flowchart (560 KB, PDF).
Note: These tools are intended for Veterans and their caregivers. They are provided for information purposes only. They should not be used as a substitute for evaluation and treatment by a healthcare professional. Your privacy is protected: The self assessment tool does not capture identifiable information in any manner.
How flu is spread
When a person with flu sneezes, coughs, talks, or laughs, flu virus can spread into the air as droplets. The droplets can spread to people and surfaces up to 6 feet away. Flu virus can spread to your hands if you touch anything that has the virus on it. If you then touch your eyes, nose, or mouth, you might get the flu.
People can spread flu to others about 1 day before they feel sick and up to 5 days after getting sick.
Who is most at risk for severe infection?
If you're in a high-risk group, you can become extremely ill from the flu. Be sure to take special precaution to prevent flu if you have any of the following conditions:
- Chronic bronchitis
- Heart disease
- Kidney disease
- Lung disease
- Weakened immune systems
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