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How to Tell the Difference Between the Flu and a Cold?


The CDC provides information on how to discriminate between the flu and the ‘common cold’. Both conditions are viral in origin. Co-infection with bacteria is possible and in the case of infection with influenza virus, can lead to significant and serious complications.  

‘Signs and Symptoms’ Comparisons

Influenza Cold
Symptom onset Abrupt Gradual
Fever Usual Rare
Aches Usual Slight
Chills Fairly common Uncommon
Fatigue, weakness Usual Sometimes
Sneezing Sometimes Common
Stuffy nose Sometimes Common
Sore throat Sometimes Common
Chest discomfort, cough Common Mild to moderate
Headache Common Rare

Credit: Centers for Disease Control and Prevention


Flu Symptoms  

Patient may experience just a few or many 

  • Fever or feeling feverish/chills 
  • Cough 
  • Sore throat 
  • Runny or stuffy nose 
  • Muscle or body aches 
  • Headaches 
  • Fatigue (tiredness) 
  • Some people may have vomiting and diarrhea, though this is more common in children than adults

Note: Not everyone with flu will have a fever

Flu Complications 

  • Moderate complications 
    • Sinus and ear infections  
  • Serious flu complications (can result from either influenza virus infection alone or from co-infection of flu virus and bacteria) 
    • Pneumonia 
    • Heart inflammation (myocarditis) 
    • Brain inflammation (encephalitis)  
    • Muscle inflammation (myositis, rhabdomyolysis)  
    • Multi-organ failure (e.g., respiratory and kidney failure) 
    • Sepsis 
    • Exacerbation of chronic medical problems  
      • Asthma attacks  
      • Worsening of heart disease  

High Risk Categories  

The following are at high risk of complications related to influenza virus infection 

  • Young children 
  • Adults aged 65 years and older  
  • Pregnant women are at especially high risk 

Note: To see the comprehensive list of high risk flu categories (and more), see the CDC Emergency Advisory below in the ‘Related ObG Topics’ section

Learn More – Primary Sources:  

CDC: What is the difference between a cold and the flu?

CDC: Information for Health Professionals