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.


  • 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.


  • 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.


  • 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


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.

Related Information

UCSF Clinics & Centers

Primary Care

Family Medicine at Lakeshore
1569 Sloat Blvd., Suite 333
San Francisco, CA 94132
New Patient Appointments:
(844) 727-8273 (PCP-UCSF)
Phone: (415) 353-9339
Fax: (415) 353-3450

General Internal Medicine at Post Street
1545 Divisadero St., First and Second Floors
San Francisco, CA 94115
New Patient Appointments:
(844) 727-8273 (PCP-UCSF)
Office: (415) 353–7900
Fax, First Floor: (415) 353–2583
Fax, Second Floor: (415) 353–2640

Center for Geriatric Care
3575 Geary Boulevard, First Floor
San Francisco, CA 94118
New Patient Appointments:
(844) 727-8273 (PCP-UCSF)
Office: (415) 353-4900
Fax: (415) 353-8101

Primary Care at Laurel Village
3490 California Street, Suite 200
San Francisco, CA 94118
New Patient Appointments:
(844) 727-8273 (PCP-UCSF)
Office: (415) 514-6200
Fax: (415) 514-6410

Screening and Acute Care
400 Parnassus Ave., First Floor
San Francisco, CA 94122
Phone: (415) 353-2602
Fax: (415) 353-2699