6 Textbook Symptoms of the Seasonal Flu

It’s easy to confuse flu symptoms with other illnesses.

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The flu affects millions of Americans each year, causing missed days at work or school, hospitalizations, and in some cases, even death. Despite the ubiquity of the flu each year, it’s still easy to confuse some of the symptoms with other illnesses.

Influenza is caused by a highly contagious virus that enters the body through the mouth or nose. There are several subtypes and strains of the flu, and some strains are known for causing more severe symptoms than others. Learn more about what the flu is here.

When the immune system kicks into gear to fight off the virus, it results in some classic symptoms, such as:

  • Fever and chills

  • Headache and body aches

  • Fatigue

  • Sore throat

  • Runny or stuffy nose

  • Or cough.

Not everyone with the flu experiences all of the above symptoms. While fever is common, you don’t have to have a fever to have the flu, and symptoms like cough or sore throat are less common among people with the flu than body aches.

Symptoms usually fade away in two weeks or fewer on their own, although some treatments are available that can help reduce the strength and duration of the symptoms. Learn more about flu treatment here.

Common Cold vs. the Flu

Usually, the knock-you-out nature of the flu makes it pretty distinct from your average common cold, but sometimes it’s hard to tell a bad cold from a mild flu infection. They’re both respiratory infections with pretty similar symptoms.

Here are the primary differences between the cold and the flu, according to the Centers for Disease Control and Prevention:

  • Fever is more common with the flu; it is rare with a cold.

  • Body aches are a textbook symptom of the flu; they are rare with a cold.

  • Sneezing and runny nose are common with the cold; they are less common with the flu.

  • Headache is common with the flu; it is rare with a cold.

Complications of the Flu

For most people, the flu is just something that causes them to feel really crummy and be stuck at home for a few days. Unfortunately, what makes the flu so serious is that it can lead to dangerous complications.

Common complications of the flu include sinus and ear infections, pneumonia, organ failure, sepsis, and inflammation of the heart, brain, or muscle tissue. The flu can also worsen conditions for people with asthma, COPD, or heart disease.

People at a high risk for complications of the flu include people who are over the age of 65, are under the age of 5, are pregnant, or have a chronic medical condition (like asthma, diabetes, heart disease, or COPD).

Worried about complications? Here are signs your kid’s flu is serious.