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Early Signs of the Flu

Each year the flu virus affects Americans with symptoms ranging from fever, chills, muscle aches, cough and headache. Because the earlier you treat the flu, the sooner you can begin to improve, it is important to recognize the early signs of the flu.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


A fever is one of the earliest symptoms to appear with the flu and often one of the first to go away. According to, a flu's fever may reach temperatures of up to 104 degrees Fahrenheit and usually goes away within 2 to 3 days 1.

Headache/Body Ache

Causes of Fever, Headache and Dry Cough

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The flu may begin with general aches, such as a headache or body aches. This pain is typically dull and throbbing, and you may mistake it for fatigue or a cold.

Dry Cough

Another first symptom of flu is a dry cough that does not produce any phlegm or mucus. Unlike a fever, this symptom does not always go away within a few days of onset and may last up to a week.


A Productive Cough and the Flu

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Unexplained shivering or feelings of coldness with no outside temperature difference (the chills) can be another early flu symptom.

Early Treatments

One of the best reasons to recognize early flu symptoms is that antiviral medications, such as Tamiflu, can be prescribed if the flu is detected within 48 hours of its onset. Antiviral medications have proven effective in reducing the overall length of flu symptoms.

Read more: 4 Things You Need to Know About the Flu Incubation Period