Influenza (or the flu) is a contagious respiratory virus that can cause mild to severe symptoms, including difficulty breathing or shortness of breath. In some cases, the flu can even lead to death, especially for those at higher risk like older adults, young children, or individuals with chronic conditions. Practicing good hygiene, such as remembering to wash your hands regularly and covering your mouth when you cough or sneeze, can help prevent the flu and other viruses.
When you’re feeling sick, it’s important to know which illness you have so you can get the best care. Banner Health can help guide you through recognizing long-term symptoms, such as lingering fatigue, and determining if medical care is necessary. We can help you differentiate between flu symptoms and those of other illnesses like the common cold, COVID-19 or viral gastroenteritis (stomach flu).
Influenza viruses cause the flu. These viruses may cause a range of symptoms that often appear suddenly and quickly get worse. For example, you may feel fine in the morning but feel very sick by the afternoon.
Common flu symptoms include the following:
Flu symptoms often appear within one to four days after exposure to a flu virus. These symptoms may last for several days and up to two weeks.
Most people who get the flu will get better within one to two weeks. Still, some people are at an increased risk of severe complications, including young children, pregnant people, older adults and people with chronic medical conditions and/or weakened immune systems.
These complications can include:
At first, the flu can often be mistaken for a bad cold or out-of-control allergies. Here is how the flu differs from other health conditions and illnesses.
The flu and the common cold share similar symptoms, such as a runny or stuffy nose, cough and sore throat. However, flu symptoms are more severe and appear more suddenly than a common cold. Fever, body aches and fatigue are also stronger with the flu.
COVID-19 and the flu are both respiratory illnesses caused by different viruses. While they share some symptoms like fever, cough and fatigue, COVID-19 causes more symptoms than the flu, including loss of taste or smell, shortness of breath and digestive issues.
COVID-19 has a higher risk of severe illness and complications than the flu.
The best way to determine which virus you have is to take a rapid or PCR test.
Triggered by exposure to allergens like pollen, dust or pet dander, allergies can cause symptoms that resemble the flu, such as a runny or stuffy nose, sneezing and coughing. However, allergy symptoms typically include itchy or watery eyes and don’t cause fever or body aches.
The flu is a viral infection, while pneumonia is a lung infection that can develop from bacterial or viral infection. The flu can sometimes progress to pneumonia, which can cause symptoms like the flu but with additional and often more severe breathing problems.
The flu tends to come on suddenly, while pneumonia develops more slowly. Muscle aches and fatigue accompany the flu, while pneumonia symptoms tend to center around the lungs.
Stomach flu (also known as viral gastroenteritis) is caused by viruses that primarily affect the digestive (gastrointestinal) system. It leads to symptoms like nausea, vomiting, diarrhea and stomach cramps. Unlike the flu, stomach flu rarely causes chest problems like cough or sore throat.
Bird flu, or avian influenza, primarily affects birds. While some types of bird flu can infect humans, they are different from the seasonal flu strains that spread among people.
Avian influenza usually spreads among birds through contact with infected birds or their waste. Occasionally, certain types of bird flu can infect humans who have close contact with infected birds or contaminated areas.
Human cases of bird flu can range from mild illness to severe respiratory problems and, in rare cases, death. It's important to understand that avian influenza is not the same as the common flu that affects humans each year, although both are caused by influenza viruses.
While most cases of the flu can be managed at home, there are instances when medical attention is necessary.
Contact your health care provider or visit your nearest urgent care if you or a loved one experiences the following:
If you have flu-like symptoms and are at high risk for complications, you should contact your health care provider for care as soon as possible.
Learn more about when to seek medical treatment.
Even if you know you’ve recently had the flu, there are still many good reasons to get a flu shot. That’s because several strains of the flu circulate each season.
Catching the flu does give you some protection, but the flu shot boosts your defense against the most widespread strains of the year. This can help keep you healthy for the rest of the season.
Learn more about flu vaccination and common myths and facts about flu shots.
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