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Patient Education

Cold or Flu?

Colds and flu are both highly contagious and, in the initial stages, a bad cold and a mild case of the flu might seem alike. However, unlike a cold, the flu is a serious illness that can have life-threatening complications. Here is a comparison of cold and flu symptoms.

Fever

  • Cold Having a fever is rare in adults and older children who come down with a cold. However, infants and small children may have a fever as high as 102 degrees Fahrenheit.
  • Flu Fever is often a symptom of the flu and is usually around 102 degrees Fahrenheit, but can go up to 104 degrees Fahrenheit. In addition, fever with the flu usually lasts three to four days.

Headache

  • Cold Headaches are rare when you have a cold.
  • Flu With the flu, headaches are common, can come on suddenly and may be rather severe.

Muscle Aches

  • Cold Muscle aches are usually mild when you have a cold.
  • Flu Muscle aches are common and often severe with the flu.

Feeling Tired and Weak

  • Cold Although you may be tired and weak with a cold, this feeling often is rather mild and never turns into extreme exhaustion.
  • Flu It is extremely common to be tired and weak when you have the flu. This feeling can last for two or more weeks. In addition, you may have extreme exhaustion that comes on suddenly.

Runny Nose, Sore Throat and Sneezing

  • Cold It is common to have a runny nose and a sore throat as well as to sneeze often when you have a cold.
  • Flu With the flu, you may have a runny nose, sore throat and sneezing.

Cough

  • Cold A mild hacking cough often accompanies a cold.
  • Flu When you have the flu, coughing is common and can become severe.

This information was adapted from the Centers for Disease Control and Prevention (CDC) Web site. For more information, visit www.cdc.gov/flu.

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.

Recommended reading

Can You Tell If It’s the Flu or COVID-19?

UCSF experts help explain the differences between flu and COVID-19, when to get a test, and why you shouldn’t try to diagnose yourself.

Facts About the Flu

Find facts about influenza, aka "the flu," including, prevention, signs and symptoms, transmission, diagnosis, treatment and complications. Learn more here.

When to Call Your Doctor About the Flu

If you are at special risk of flu complications, contact your doctor as soon as your symptoms begin. Learn more here.

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Primary Care at Laurel Village

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Did you know?

At any given time, UCSF is conducting more than 1,500 clinical trials to better understand disease and evaluate new treatments. Many treatments and diagnostic tools developed at UCSF are now in standard use around the world, while others are still only available here or at a handful of medical centers.

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