Symptoms of Flu

The symptoms of flu are somewhat similar to the symptoms of a common cold, but may come on more suddenly, and are often more severe. However, some cases of flu can also be mild. Typical symptoms may include some of:

Less common symptoms that are possible in adults include:



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Back to: « Flu

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Seasonal Flu

Source: NIH News in Health (NIH)1

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Symptoms include fever, chills, body aches, runny nose, sore throat, headache and extreme exhaustion. Symptoms include fever, chills, body aches, runny nose, sore throat, headache and extreme exhaustion.

Source: NIH News in Health (NIH)2

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People infected with the seasonal flu virus feel miserable with fever, chills, muscle aches, coughing, congestion, headache and fatigue for a week or so.

Source: NIAID (NIH)3

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People with influenza commonly have acute onset of fever, myalgia, headache, and cough.

Source: CDC Yellow Book 20164

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CLINICAL PRESENTATION

Uncomplicated influenza illness is characterized by the abrupt onset of signs and symptoms that include fever, muscle aches, headache, malaise, nonproductive cough, sore throat, vomiting, and rhinitis.

Illness without fever can occur, especially in the elderly.

Children are more likely than adults to also experience nausea, vomiting, or diarrhea when ill with influenza.

Physical findings are predominantly localized to the respiratory tract and include nasal discharge, pharyngeal inflammation without exudates, and occasionally rales on chest auscultation.

The incubation period is usually 1-4 days after exposure.

Influenza illness typically resolves within 1 week for most previously healthy children and adults who do not receive antiviral medication, although cough and malaise can persist for >2 weeks, especially in the elderly.

Source: CDC Yellow Book 20165

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If you have cancer now or have had cancer in the past, you are at higher risk for complications from the seasonal flu or influenza, including hospitalization and death. Flu symptoms include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, and fatigue. Some people may have vomiting and diarrhea. People may be infected with the flu and have respiratory symptoms without a fever.

Source: CDC Cancer6

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Flu Symptoms

Influenza (also known as the flu) is a contagious respiratory illness caused by flu viruses. It can cause mild to severe illness, and at times can lead to death. The flu is different from a cold. The flu usually comes on suddenly. People who have the flu often feel some or all of these symptoms:

Source: CDC7

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What are the emergency warning signs of flu sickness?

In children

In adults

In addition to the signs above, get medical help right away for any infant who has any of these signs:

Source: CDC8

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Influenza Symptoms

Influenza (also known as the flu) is a contagious respiratory illness caused by flu viruses. It can cause mild to severe illness, and at times can lead to death. The flu is different from a cold. The flu usually comes on suddenly. People who have the flu often feel some or all of these symptoms:

Source: CDC9

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Signs and Symptoms

Symptoms usually appear 1 to 3 days after being infected.

The symptoms of flu can include:

In the elderly, fever may be absent and the only signs of flu may be:

Children are more likely to have gastrointestinal symptoms (nausea, vomiting and diarrhoea).

Source: Queensland Health10

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Flu and pneumonia may cause:

Source: NIA (NIH)11

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Flu—short for influenza—is a virus that can cause fever, chills, sore throat, stuffy nose, headache, and muscle aches. Flu is very serious when it gets in your lungs.

Source: NIA (NIH)12

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Flu Signs and Symptoms

If you do become sick with the flu, you may experience some or all of the following symptoms:

Source: MedLinePlus Magazine (NIH)13

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Signs and Symptoms of Flu

People who have the flu often feel some or all of these signs and symptoms:

Some people may have vomiting and diarrhea, though this is more common in children than adults.

*It's important to note that not everyone with flu will have a fever.

Source: MedLinePlus Magazine (NIH)14

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The flu is different from a cold, and typically comes on suddenly and may include the following symptoms:

Source: MedLinePlus Magazine (NIH)15

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The flu usually develops more quickly. You’ll have fever and muscle aches within a few hours and will generally feel sicker than with a cold.

Source: New Zealand Health16

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The influenza virus infects your nose, throat and lungs. The flu is normally worse than a cold.

Source: New Zealand Health17

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Symptoms of influenza come on suddenly and can include fever, chills, muscle aches, runny nose, cough and stomach upsets.

Source: New Zealand Health18

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Check if you have flu

Flu symptoms come on very quickly and can include:

The symptoms are similar for children, but they can also get pain in their ear and appear less active.

Source: NHS Choices UK19

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Symptoms

Influenza is a respiratory illness and commonly has a sudden onset. Symptoms include headache, fever, cough, sore throat, aching muscles and joints and tiredness.

Source: GOV.UK20

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Influenza (flu) is a viral infection affecting the lungs and airways. The symptoms can appear very quickly and include:

Source: GOV.UK21

Incubation Period of Flu

The incubation period is usually 1-4 days after exposure.

Source: CDC Yellow Book 201622

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Incubation period is between 1 to 3 days.

Source: GOV.UK23

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References

  1. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ issue/ oct2014/ feature2
  2. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ 2005/ October2005/ docs/ 01features_01.htm
  3. Source: NIAID (NIH): niaid.nih.gov/ diseases-conditions/ influenza
  4. Source: CDC Yellow Book 2016: cdc.gov/ travel/ yellowbook/ 2016/ the-pre-travel-consultation/ respiratory-infections
  5. Source: CDC Yellow Book 2016: cdc.gov/ travel/ yellowbook/ 2016/ infectious-diseases-related-to-travel/ influenza
  6. Source: CDC Cancer: cdc.gov/ cancer/ flu/ symptoms.htm
  7. Source: CDC: cdc.gov/ flu/ consumer/ symptoms.htm
  8. ibid.
  9. Source: CDC: cdc.gov/ flu/ about/ disease/ complications.htm
  10. Source: Queensland Health: conditions.health.qld.gov.au/ HealthCondition/ condition/ 8/ 118/ 82/ influenza-the-flu
  11. Source: NIA (NIH): nia.nih.gov/ health/ alzheimers-disease-common-medical-problems
  12. Source: NIA (NIH): nia.nih.gov/ health/ shots-safety
  13. Source: MedLinePlus Magazine (NIH): medlineplus.gov/ magazine/ issues/ winter16/ articles/ winter16pg12-13.html
  14. Source: MedLinePlus Magazine (NIH): medlineplus.gov/ magazine/ issues/ fall14/ articles/ fall14pg10-11.html
  15. Source: MedLinePlus Magazine (NIH): medlineplus.gov/ magazine/ issues/ fall06/ articles/ fall06pg18-21.html
  16. Source: New Zealand Health: health.govt.nz/ your-health/ conditions-and-treatments/ diseases-and-illnesses/ colds
  17. Source: New Zealand Health: health.govt.nz/ your-health/ conditions-and-treatments/ diseases-and-illnesses/ influenza
  18. ibid.
  19. Source: NHS Choices UK: nhs.uk/ conditions/ Flu/ 
  20. Source: GOV.UK: gov.uk/ government/ publications/ health-protection-in-schools-and-other-childcare-facilities/ chapter-9-managing-specific-infectious-diseases
  21. Source: GOV.UK: gov.uk/ government/ collections/ seasonal-influenza-guidance-data-and-analysis
  22. Source: CDC Yellow Book 2016: cdc.gov/ travel/ yellowbook/ 2016/ infectious-diseases-related-to-travel/ influenza
  23. Source: GOV.UK: gov.uk/ government/ publications/ health-protection-in-schools-and-other-childcare-facilities/ chapter-9-managing-specific-infectious-diseases

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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.