(tense music) Pneumonia is a common infection that can affect one or both of your lungs at the same time. Your symptoms may vary depending on the type of pneumonia you have and other factors, like your age, the strength of your immune system, and other underlying medical conditions you have. Here are four common warning signs of pneumonia. Number one, you have chest pain that gets worse whenever you cough, sneeze, or take a deep breath. When you have pneumonia, small air sacs in your lungs, called alveoli, become inflamed and swell. When this happens, it makes it hard for you to breathe, adding additional increased pressure and irritating your lungs and chest. Number two, you cough up phlegm, mucus, or blood. Your alveoli will fill with fluid, pus, or mucus as a side effect of your immune system fighting off your lung infection, so it's common to cough this stuff up and even cough up a small amount of blood when you have increased inflammation in your lungs. Number three, you have fever and/or chills. Infections and changes to your oxygen levels all have an impact on your blood pressure and the way the rest of your body functions. You may develop a fever or chills. In older adults especially, it's common to experience lower body temperatures or other systemic symptoms, like fatigue, confusion, or dizziness when you have pneumonia. Number four, you've lost your appetite. When your body is fighting off a lung infection, you may not have the stomach for some of the same foods you normally enjoy. You may feel nauseous or even have bouts of vomiting or diarrhea. When you have pneumonia, it's important that you seek medical treatment right away and get enough rest for your body to recover. (light music)