You have these symptoms, and you also have a weakened immune system because of cancer, diabetes, AIDS, or other conditions.
You have symptoms and a serious illness like chronic heart or kidney disease, trouble breathing, cystic fibrosis, or chronic anemia. You’re more likely to have problems with the flu, and your doctor should watch you closely.
Your fever lasts more than 3 or 4 days, you get short of breath while resting, and you have chest pain. You may have pneumonia.
Your nasal drainage is yellow or green and has lasted for more than 10 days. You could have a sinus infection.