Influenza is a viral infection that attacks your respiratory system, including your nose, throat and lungs. Influenza is commonly called the flu, but it's not the same as stomach flu, which is an intestinal infection marked by watery diarrhea, abdominal cramps, nausea or vomiting, and sometimes fever.
For most people, the flu resolves on its own. But sometimes the flu and its complications can be deadly. People at higher risk of developing flu complications include young children, pregnant woman and those two weeks postpartum, people over 65, people with weakened immune systems and some chronic illnesses, and people who are obese. If you have flu symptoms and are at risk of complications, contact your health care provider as soon as possible