Flu vs. Pneumonia: How Can You Tell the Difference?

Influenza and pneumonia have some common symptoms, but they are not the same. Knowing which illness is which will help you get timely, appropriate care and avoid complications. 

When you find yourself coughing and running a fever, flu or pneumonia could be responsible. To get the treatment you need, and lower the risk of serious complications from either condition, it is important to understand the differences between flu versus pneumonia symptoms. The causes can differ as well. Flu is caused by viruses, but pneumonia can be caused by viruses, bacteria, or fungi. In addition, pneumonia can develop as a flu complication.

Abnormal Body Temperatures, Chills, and Sweating

You can run a fever with either flu or pneumonia, but lowered body temperatures may be experienced by people with weakened immune systems, and by seniors 65 and older. If you develop a fever, 100.4° or higher is common with the flu—but it should last for 48 hours or less. If your fever climbs to 102° or higher, and lasts longer, you may have pneumonia. Both illnesses cause chills and sweating.

Soreness and Pain

Sore muscles in your legs, arms, and elsewhere are common with flu symptoms. By contrast, pneumonia typically causes pain in the chest. This is especially noticeable as you cough, or even just breathe normally. You may also feel pain in your ribs from frequent, hard coughing.


You will find yourself coughing whether you have flu or pneumonia. A flu cough is likely to be “dry,” though (in other words, you will not hear or feel a “rattle” in your chest and, if you try to spit, no phlegm will come up). With pneumonia, if you are not dehydrated, your cough is likely to bring up phlegm that has built up in your lungs. Fluid buildup may also cause shortness of breath with pneumonia.

Lethargy and Weakness

With both flu and pneumonia, you are likely to feel excessively tired and to experience general feelings of weakness. Such symptoms are to be expected as your immune system works overtime to overcome these illnesses.

Nasal Congestion and Sore Throat

With pneumonia, unlike the flu, your sinuses are likely to stay clear. Your throat may become sore from excessive coughing, but you will probably not experience a red or inflamed throat as you would with the flu. Pneumonia causes an infection in the lungs, which produces coughing and breathing difficulties, rather than cold-like symptoms that affect the nose and throat.

Nausea and Vomiting

If you have “stomach flu” (gastroenteritis), you are likely to experience digestive upsets such as cramps, pain, and vomiting. These can occur with pneumonia as well, along with diarrhea.

Headache and Confusion

Headaches, sometimes severe, can occur with both flu and pneumonia. Confusion, difficulty with short-term memory, or other changes in cognition sometimes occur with pneumonia, especially for seniors 65 and older.

Viral vs. Bacterial Pneumonia

Different causes will produce different  symptoms of pneumonia. Viral pneumonia usually causes milder symptoms, such as a dry cough and light chest congestion. Bacterial pneumonia is known to cause more severe symptoms, such as chest pain, difficult breathing, a high or persistent fever, and greenish or yellowish phlegm. When pneumonia develops as a complication of flu, it is more likely to be bacterial rather than viral pneumonia.

Symptom Time Frame

You should seek medical care if your symptoms last longer than three to five days, especially if they are severe. Diagnostic tests can be performed in a doctor’s office to determine whether you have flu or pneumonia, and which type of pneumonia you may have. Test results will determine the most effective course of treatment.

When you think you have the flu or pneumonia, or if you simply wish to get a flu vaccination, never hesitate to make an appointment with a family practitioner, contact ARcare at (501) 286-6121. We have been providing accessible medical and dental care in Arkansas since 1986, and our staff is on call 24 hours a day.

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