Diagnosing Influenza

Most of the time, a doctor can diagnose influenza, or the flu, based on your symptoms—especially when they occur in January or February, the peak months of flu season. Symptoms include fever, chills, fatigue, body aches, cough, sore throat, and a runny or stuffy nose. Some people may also experience nausea, vomiting, or diarrhea.

The flu and the common cold share symptoms, but those associated with the flu tend to be more severe. A fever, body aches, fatigue, and cough are more common with the flu, and they often come on suddenly.

Your NYU Langone doctor may order tests to confirm that you have the flu if you’re in the hospital or you’re at risk for complications. People at risk for complications include those who are 65 or older; young children between the ages of 6 months and 5 years; pregnant women; people with disabilities; and those with chronic health conditions, such as diabetes or heart disease.

Complications of influenza can be serious, and sometimes life threatening. They may include bacterial pneumonia, a lung infection, ear or sinus infections, and dehydration. They may also include worsening of existing conditions, such as diabetes, congestive heart failure, and chronic lung diseases.

Influenza Test

An influenza test helps doctors determine if you have the flu virus. Your doctor wipes the inside of your nose or back of your throat with a swab to obtain a sample of nasal secretions or mucus, then sends the sample to a lab for testing. The results enable a doctor to distinguish the flu virus from other respiratory infections with similar symptoms, such as adenoviruses and non-polio enteroviruses.

Chest X-ray

People at risk for complications who have lung-related symptoms, such as coughing or difficulty breathing, may need a chest X-ray. This test, which uses electromagnetic radiation to create images of the body, enables the doctor to determine if pneumonia, not the flu, is causing your symptoms.

More Influenza Resources

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