Symptoms of pneumonia caused by bacteria in otherwise healthy people younger than 65 usually come on suddenly. They often start during or after an upper respiratory infection, such as influenza or a cold, and may include:
Cough, often producing mucus (sputum) from the lungs. Mucus may be rusty or green or tinged with blood.
Fever, which may be less common in older adults.
Shaking, "teeth-chattering" chills (one time only or many times).
Fast, often shallow, breathing and the feeling of being short of breath.
Chest wall pain that is often made worse by coughing or breathing in.
Fast heartbeat.
Feeling very tired (fatigue) or feeling very weak (malaise).
Nausea and vomiting.
Diarrhea.
Symptoms of pneumonia not caused by bacteria (nonbacterial) include fever, cough, shortness of breath, and little mucus when you cough. They may come on gradually and are often less obvious and less severe than those of bacterial pneumonia. Many people don't know that they have nonbacterial pneumonia because they do not feel sick.
When symptoms are mild, your doctor may call your condition "walking pneumonia."
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There it is in a nutshell.
I've witnessed bacterial pneumonia with that sudden onset of symptoms.. hubby scared the crap out of me a few years ago. Month in hospital, chest tubes, surgery on lungs, ventilator support.... It's the one time that I truly thought he would die.
Leave it to my husband to make things more difficult... he got a weird virus that only DOGS get as part of that pneumonia.
Sit, roll over, play dead (oh wait.. don't!)