What are the differences between the flu and pneumonia?

Flu and pneumonia do share a lot of similarities. They both have high fever with chills and you feel really crummy when you have both. Typically though, with pneumonia, you have a cough with sputum production, which is where you bring something up after you cough. Whereas with the flu, you might have a little bit of a cough, but it’s mostly fatigue, weakness, nausea and basically feeling like you got hit by a truck.