You thought your cold was clearing up, but now you feel much worse: You’re coughing, you have a fever and chills, and it’s difficult to breathe. Are you having a relapse, or is this something more serious?\nIf you’ve previously been sick with a\u00a0cold or the flu \u2014 or if you suddenly feel ill \u2014 you could have pneumonia.\nWhat Is Pneumonia?\nPneumonia is an infection that can affect one or both of your lungs. Bacteria, a virus, or even fungi can trigger pneumonia. In the United States, bacterial pneumonia is commonly the result of infection with Streptococcus pneumoniae bacteria. The viruses that cause colds and flu can also cause pneumonia, which usually results in a more mild form of the condition. Fungi \u2014 inhaled from soil or bird droppings \u2014 can also be to blame, typically in people with weakened immune systems.\nPneumonia is lung inflammation caused by bacterial or viral infection.\nPneumonia Symptoms: Warning Signs to Know\nAll types of pneumonia can cause the air sacs in the lungs to fill with fluid or pus. When this occurs, you can develop a variety of symptoms, ranging from mild to debilitating. They can include:\n\nCoughing, often with phlegm\nA high fever\nChills and shaking\nChest pain when you cough or breathe\nShortness of breath\nFatigue\n\nRELATED:\u00a0High Fever? When Should You Worry?\nWhich People Are More Likely to Get Pneumonia?\nAlthough anyone can get pneumonia, it is more common in certain groups. Children younger than age 2 and people older than age 65 are most likely to develop it. Certain factors can also increase your risk of pneumonia, such as:\n\nHaving a weakened immune system. This is usually a problem for people who have HIV\/AIDS, who are alcoholic, who have had an organ transplant, or who have undergone chemotherapy or long-term treatment with steroids or other immunosuppressant drugs.\nBeing hospitalized or being on a ventilator\nHaving a chronic condition including asthma, chronic obstructive pulmonary disease, structural lung disease and heart disease\nSmoking\n\nPneumonia Prevention\nWith proper treatment, pneumonia will clear up in most people. However, it can cause complications, particularly in those who are in the high-risk groups mentioned above. Complications can include severe difficulty breathing, fluid build-up around the lungs, a lung abscess, and the spread of bacteria to the blood and other organs. In some cases, pneumonia can be fatal.\nFor these reasons, it’s crucial to seek prompt treatment if you think you have pneumonia \u2014 and to take steps to prevent it in the first place. Your doctor may use a variety of tests to diagnose the problem, including a physical exam, blood tests, and chest X-rays.\n\nHow Your Doctor Treats Pneumonia\nThe treatment you receive depends on the type of pneumonia you have, as well as your age, general health, and the severity of your symptoms. Most people with pneumonia can be treated at home and will recover in a few days to a few weeks. Treatments include:\n\nAntibiotics to treat bacterial infections\nCough medicine to help ease but not eliminate coughing (some coughing is beneficial because it helps move fluid out of your lungs)\nPain relievers to help lower a fever and relieve discomfort\nSelf-care measures, such as getting plenty of rest and staying hydrated\n\nIf you believe you are sick, find a doctor at UPMC.