Free PcMED Insider NewsletterClick here
Alerts Allergy And Immunology Cancer Screening Cardiology Cervical Cancer Screening Dermatology Diabetes Endocrine ENT Evidence Matters General Internal Medicine Genetics Geriatrics GI PcMED Connect GU Hematology ID Medical Legal Mental Health MSK Nephrology Neurology FAQs@PcMED PrEP Resource Center PrEP for Physicians PrEP for Patients Preventive Medicine Pulmonary Rheumatology Test Your Knowledge Vaccinations Women's Health Your Practice

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

Symptom onsetAbruptGradual
ChillsFairly commonUncommon
Fatigue, weaknessUsualSometimes
Stuffy noseSometimesCommon
Sore throatSometimesCommon
Chest discomfort, coughCommonMild to moderate

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