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What are the symptoms of the flu?

Dr. Alan M. Young, MD
Family Practitioner

Flu (influenza) symptoms typically include a high fever (usually 102 degrees Fahrenheit or higher), headaches, muscle aches and chills. Those are usually the early onset symptoms, which are often followed by a cough, sore throat and loss of appetite.

There's always a lot of confusion with the term flu. A lot of people will take that to mean a stomach flu, which causes vomiting, diarrhea and sometimes abdominal pain. That would not be the true symptoms of the flu in the medical profession. When doctors say flu, they mean influenza.

Symptoms of influenza can include:

  • fever
  • cough
  • sore throat
  • runny or stuffy nose
  • body aches
  • headache
  • chills
  • fatigue
  • some people may also have vomiting and diarrhea.

People may be infected with the flu and have some symptoms without a fever.

Symptoms of the flu include:
  • fever
  • chills
  • muscle aches
  • headache
  • fatigue
  • a general unwell feeling called malaise
  • cough
  • runny nose
  • sore throat

While influenza and the common cold are both caused by respiratory viruses, flu symptoms are significantly more severe. Although both illnesses can produce runny or stuffy noses and coughs, flu symptoms often also include high fevers (over 102º F), body aches, sore throat, vomiting and diarrhea.

For most adults, the influenza virus means a week or so of fever, sore throat, cough, headache and body aches. But for children, the flu can have much more serious consequences, such as ear infections, dehydration, pneumonia or death.

Influenza ("the flu" for short) is a common respiratory infection caused by a virus. Flu symptoms include:

  • Fever and/or chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Body aches and/or headache
  • Fatigue
  • Diarrhea and vomiting
Dr. Joel H. Fuhrman, MD
Family Practitioner

Symptoms of the flu include:

  • High fever
  • Headache
  • Extreme fatigue
  • Muscle aches
  • Cough, sore throat, and nasal congestion are also common
  • Gastrointestinal symptoms, such as nausea, vomiting, and diarrhea, are more common in children
  • Severe headaches and muscle aches usually differentiate the flu from other viral illnesses and colds
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Stacy Wiegman, PharmD
Pharmacy Specialist

Influenza, better known as the flu, can cause the following symptoms:

  • fever
  • fatigue
  • headaches and body aches
  • cough
  • sore throat
  • runny nose
  • stuffed-up nose

Vomiting and diarrhea are possible symptoms of the flu, too, though they're more common in children. The symptoms of the flu can come on very quickly.

Symptoms of influenza (flu) can include:

  • fever
  • cough
  • sore throat
  • runny or stuffy nose
  • body aches
  • headache
  • chills
  • fatigue
  • some people may also have vomiting and diarrhea.

People may be infected with the flu, including 2009 H1N1 flu, and have respiratory symptoms without a fever.

The symptoms of influenza (flu) include a high fever, often over 103 for children; cough; chills; and muscle aches. People with influenza may also experience fatigue, low appetite, headaches, and nasal symptoms such as a runny nose or congestion. In children, influenza can produce digestive problems such as nausea, vomiting, and diarrhea.

The symptoms of the flu for adults include:

  • runny or stuffy nose
  • sore throat
  • chills
  • mild or severe body aches
  • cough
  • fever
  • diarrhea or vomiting
  • difficulty breathing
  • dizziness or confusion
  • severe headache
  • a return and worsening of symptoms after they've improved

For children, additional symptoms may include:

  • fever with rash
  • fast or labored breathing
  • unable to eat
  • no tears when crying
  • not drinking enough fluids
  • not waking up or not interacting
  • excessively irritable or doesn't want to be held
  • bluish skin color
  • significantly fewer wet diapers than normal
  • a return and worsening of symptoms after they've improved

Symptoms of the flu include muscle and joint pain, high fever, a deep cough, chills, fatigue and weakness. These symptoms usually send you straight to bed for three to five days or longer. Afterward, cough and tiredness may persist for days or even weeks. Other symptoms include headache, eye pain and sometimes a stuffy nose and sore throat. Some strains of the flu also produce vomiting and diarrhea. Symptoms usually come on suddenly once you've been exposed to the virus.

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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.