It’s cold and flu season again and you’re feeling that familiar ache coming on. Is it a cold? Is it the flu? How can you tell?
While even medical professionals can have a hard time telling the difference between a cold and flu without laboratory testing, overall symptoms can give an idea as to what is making you feel miserable and how soon you can expect to feel better.
What is the difference between a cold and the flu?
Over 200 viruses cause colds. Rhinoviruses (literally, ‘Nose virus’) are the most common cause of colds. Cold symptoms are generally milder than ones associated with flu and tend to focus around the nose and eyes. Complications from cold viruses are generally minor, with ear or sinus infections being the most common.
Flu is caused by one family of viruses — influenza viruses. Flu symptoms are more severe and the risk for complications is higher. Flu-related complications, which include bacterial infections such as bronchitis and pneumonia, can be life threatening. These complications cause approximately 36,000 deaths and more than 200,000 hospitalizations each year in the United States alone.
Cold symptoms vs. flu symptoms: Do I have a cold or the flu?
While cold and flu symptoms are similar to each other, flu symptoms tend to be more sudden and severe. Check out the guide below to determine if you have a cold or the flu.
Onset of symptoms
Cold: Symptoms come on gradually over a few days
Flu: Symptoms come on suddenly, within 3-6 hours
Location of symptoms
Cold: Most of the symptoms are felt from the neck up
Flu: Feel sick all over
Cold: Mild fever or no fever. A more severe cold virus may produce a fever above 100 degrees F. Cold viruses rarely produce fevers higher than 101 degrees F.
Flu: A high fever is common, ranging between 100-102 degrees F or higher, and lasts for 3 to 5 days. 80% of all flu cases experience a fever.
Fever (infant or young child)
Cold: Fever between 100-102 degrees F is common in young children.
Flu: Young children may run a very high fever, in some cases reaching 106 degrees F.
Cold: A hacking, productive cough (produces mucus) is common.
Flu: A non-productive cough (does not produce mucus), often referred to as a dry cough, is common.
Flu: Common. 80% of all flu cases experience headache.
Cold: Mild body aches are common
Flu: Severe body aches are common, especially in the back, arms and legs.
Stuffy or runny nose
Cold: Usual. Nasal secretions generally become thick and yellow or green in color within 1 to 3 days of symptom onset
Flu: Sometimes. A runny nose more common in children than adults.
Flu: Common. 60% of all flu cases experience chills.
Fatigue / Weakness
Flu: Moderate to severe. Extreme exhaustion is common at the beginning of the illness.
Cold: Common. A red throat is not associated with colds.
Flu: Sometimes. A red throat can be associated with flu.
Cold: Mild to moderate.
Flu: Common, may become severe.
Length of illness
Cold: Most symptoms disappear within one week.
Flu: Initial ‘all over’ symptoms last between 2 to 4 days. Most other symptoms last between 4 to 7 days. Coughing and fatigue may continue for 2 to 3 weeks.
Cold: Colds can also produce watery or burning eyes, decreased appetite, and post-nasal drip.
Flu: The 2009 H1N1 flu virus (Swine flu), which is expected to make a reappearance in the 2010/11 flu season, has been known to produce nausea, vomiting and diarrhea in some individuals. These symptoms can also be caused by seasonal flu, but are more common in children than adults.
Additional reading and sources:
For a more detailed description of the difference between colds and flu, see the article Cold and Flu Differences by Alan Greene, MD FAAP.
For more information on influenza and its symptoms, please visit the Tamiflu website.