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.

Reviewed by health care specialists at UCSF Medical Center.

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.