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What are the differences between a cold and the flu?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

A cold, also called the common cold, and the flu, or influenza, are both infections of the respiratory system. Both colds and influenza are caused by a variety of different viruses. In addition, the symptoms of both cold and flu include a fever, cough, congestion, headaches, fatigue, and body aches. The similarities in symptoms make it difficult to distinguish one form the other.

However, with a cold, symptoms tend to be milder: body aches and fatigue are mild, the fever is lower, and the headache is less painful. People with colds have more sneezing, itchy throats, and runny noses. People with the flu experience more pronounced fatigue, higher fever, and painful headaches. In children, influenza can produce digestive problems such as nausea, vomiting, and diarrhea. Flu is also more likely to lead to complications and hospitalization.

Dr. Alan M. Young, MD
Family Practitioner

The main difference between a cold and the flu is the severity of the symptoms. Generally, a cold is going to have milder symptoms than the flu. Most of the time, a cold will start with a mild sore throat that may become increasingly more severe. After a few days, one will start to get a stuffy or runny nose and cough. Sometimes people have a low-grade fever or chills, but that would be uncommon.

Influenza, or the flu, is usually more severe. The first symptoms are usually a very high fever, shaking, chills, body aches and headaches. Nasal congestion, coughing and a sore throat may develop after a few days, but it's really the severity of the symptoms that differentiate the two.

A cold and flu are both respiratory infections caused by a virus. The main difference between them is that they are caused by different viruses. Another difference is their symptoms. Although the cold and flu share some similar symptoms such as nasal congestion and fever, the flu tends to lead to more severe symptoms. 
It's important to know the difference between the cold and flu because each illness is treated differently. You know you have the flu when you feel as though you've been hit by a truck and experience symptoms such as high fever, severe headache, muscle and body aches and extreme tiredness, along with coughing and nasal symptoms. A cold is less severe and often includes a runny nose, sneezing and coughing. Unlike flu, colds typically don't cause fever. 

Many people confuse the terms "cold" and "flu" because the illnesses share some of the same features. Both are caused by viruses that infect the respiratory tract, mainly during the winter, and both can cause symptoms such as coughing and sore throat. A cold is a minor viral infection of the nose and throat and can occur in any season. More than 200 viruses are known to cause the common cold.
Dr. Leigh Vinocur, MD
Emergency Medicine Specialist

This seasonal question is age-old: Is it a cold or is it the flu? While it often feels like you’re only choice to wait and see how sick you get, there are clues to help you differentiate one from the other. Typically, colds begin gradually with a sore throat that is rarely accompanied by a fever, headache and/or muscle aches. The main symptoms of a cold are sniffles, a runny nose and a wet sounding productive cough. Flu on the other hand, hits you like a freight train with a high fever that’s usually greater than 100-102 degrees Fahrenheit, a bad headache and muscle aches. Rarely do you have sniffles, and if there is a cough, it is usually a dry non-productive cough. The flu causes severe fatigue; you will be wiped out. Colds usually get better by 1 week at the most but the flu can linger longer. Another easy trick is if all your symptoms are occurring above your neck (such as runny nose) it’s probably a cold, if they are occurring below your neck (such as body aches) it’s probably the flu!

Some cold symptoms and flu symptoms are the same. This list will assist you in determining whether your symptoms are likely to be due to a cold or an influenza virus.

Symptoms of the flu include:
  • decreased appetite
  • runny or congested nose
  • red eyes
  • sneezing
  • headache
  • general body ache
  • dry cough
  • sudden onset of symptoms
  • pain around or behind the eyes
  • fever of 101 degrees to 104 degrees
  • intestinal disturbance
  • vomiting
  • fatigue
Symptoms of a cold include:
  • gradual onset of symptoms
  • sore throat
  • decreased appetite
  • runny or congested nose
  • red eyes
  • sneezing
  • headache
  • general body ache
  • dry cough      
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Stacy Wiegman, PharmD
Pharmacy Specialist

The common cold and the flu, or influenza, may cause many of the same symptoms. For instance, both the cold and flu can produce coughing, nasal congestion, and fatigue. However, there are some important differences between a cold and the flu, including the following:

  • The flu causes a very high fever. With the flu, your body temperature may rise over 102 degrees Fahrenheit. A cold causes only a mild fever, if any. The flu can also cause chills and sweats; a cold usually doesn't.
  • Unlike the flu, a common cold commonly causes sneezing. Headaches are rare with a cold but common with the flu.
  • When you develop a cold, the symptoms usually emerge gradually. Symptoms of the flu usually come on more suddenly.

If you have flu symptoms and you are at increased risk for complications (you have a chronic medical condition, are pregnant, or are 65 years of age or older), contact your healthcare provider. Children under age 5 are also at higher risk for complications.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.