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Conditions and Diseases
Cold and Flu
Swine Flu (H1N1/09)
The Difference Between
Viruses (biological)

What is the difference between a cold and the flu?


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October 12, 2011 3:03AM

They are caused by different viruses and have slightly different symptoms.

See related question below for the symptoms of the A-H1N1/09 "Swine Flu".

The symptoms of the cold and flu can be hard to differentiate, sometimes not even possible without a specific laboratory test to determine which virus is causing your symptoms. See the related link below for more information on this from US Flu website,

The primary differences are:

  • The flu usually causes a high fever and a cold doesn't cause a fever except in rare circumstance.
  • General aches and pains with the flu are usually present and can be severe, with a cold they are mild.
  • You may feel very fatigued from the flu and this is unusual with a cold.
  • Headaches are much more common with the flu.
  • The usual cold symptoms of stuffy or runny nose, sneezing, and sore throat are only sometimes seen with the flu.
  • A severe cough comes with the flu but is not as severe with a cold.

Colds typically begin with a sore throat. Sometimes a mild fever, cough, and/or a stuffy nose are present. It is important to note the difference between a cold and an allergy because of the different treatments associated with each. Cold symptoms can usually be controlled through the use of a decongestant and anti-inflammatory medicine (e.g. Ibuprofen). Fever is not as common in colds as in the flu. Those with colds almost always have fevers under 101 degrees Fahrenheit.

There are a few basic kinds of flu viruses but hundreds of cold viruses. Colds are usually milder than the flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems, such as pneumonia, bacterial infections, or hospitalizations, whereas this is possible with an infection with a flu virus.


LIKELY (>50% chance of these symptoms)

  • fever 102 deg. F (39 deg. C) or higher (can reach up to 107 deg. F (42 deg. C) in extreme cases)
  • dry hacking cough
  • severe runny nose
  • stuffiness
  • chills (happen during fevers when body adjusts thermostat to raise it's set point)
  • headache

POSSIBLE (30-50% chance)

  • sore throat

RARE (< 30% chance)

  • diarrhea
  • vomiting


LIKELY (>50% chance)

  • runny nose
  • stuffiness
  • coughing frequently

POSSIBLE (30-50% chance)

  • fever 99 deg. F to 101 deg. F (37.2 deg C to 38.3 deg C.)
  • chills
  • sore throat

RARE (<30% chance)

  • gastrointestinal symptoms like diarrhea and vomiting

The 'flu - an abbreviation for "influenza" - is a viral infection of the respiratory passages causing fever, severe aching, and catarrh, and often occurring in epidemics.

A cold, on the other hand, a common viral infection in which the mucous membrane of the nose and throat becomes inflamed.
Influenza (the flu) is usually a more severe illness than the common cold, which is caused by other respiratory viruses. The 'flu typically showcases symptoms including headaches, chills and cough followed rapidly by a fever, appetite loss, muscle aches and tiredness. Cold symptoms are limited to the upper respiratory tract with runny nose, sneezing, watery eyes, and throat irritation.