Influenza

Influenza, also known as the flu, is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness and can lead to complications such as pneumonia, bronchitis, and sinus and ear infections.

Types of Influenza

  • Influenza A: This type of flu virus is found in many animals, including ducks, chickens, pigs, and horses, as well as humans. Influenza A viruses are constantly changing, which means that people can get infected with the same strain multiple times.
  • Influenza B: This type of flu virus is found only in humans. Influenza B viruses also change over time, but the changes tend to be smaller than those seen in influenza A viruses.
  • Influenza C: This type of flu virus is relatively rare and typically causes mild illness. Influenza C viruses are not thought to cause human flu epidemics.

Symptoms of Influenza

The symptoms of influenza can vary from person to person, but common symptoms include:

Transmission of Influenza

Influenza viruses are spread from person to person through:

  • Respiratory droplets produced when an infected person talks, coughs, or sneezes
  • Contact with contaminated surfaces or objects and then touching one's mouth, nose, or eyes

Complications of Influenza

Certain people are at higher risk for complications from influenza, including:

  • Older adults (65 years and older)
  • Young children (under the age of 5)
  • Pregnant women
  • People with certain chronic health conditions, such as heart disease, lung disease, or diabetes
  • People with weakened immune systems, such as those with HIV/AIDS or undergoing chemotherapy

Treatment and Prevention of Influenza

Treatment for influenza typically involves:

  • Rest and hydration to help manage symptoms
  • Over-the-counter medications, such as pain relievers and decongestants, to relieve symptoms
  • Antiviral medications, such as oseltamivir (Tamiflu) or zanamivir (Relenza), which can help shorten the duration and severity of illness if started within 48 hours of symptom onset

Prevention measures include:

  • Getting vaccinated against influenza each year
  • Practicing good hygiene, such as washing hands frequently and avoiding close contact with people who are sick
  • Avoiding touching one's eyes, nose, and mouth
  • Cleaning and disinfecting surfaces and objects that may be contaminated with influenza viruses

Frequently Asked Questions (FAQs)

What is Influenza?
Influenza, also known as the flu, is a contagious respiratory illness caused by influenza viruses.

What are the symptoms of Influenza?
Symptoms include fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue.

How is Influenza spread?
Influenza can be spread through respiratory droplets when an infected person talks, coughs, or sneezes, and possibly by touching surfaces contaminated with the virus.

Who is at high risk for complications from Influenza?
Older adults, young children, pregnant women, and people with certain chronic health conditions are at higher risk for complications.

Can Influenza be prevented?
Vaccination is the most effective way to prevent influenza, but other measures like frequent handwashing and avoiding close contact with infected individuals can also help.

Is there a treatment for Influenza?
Antiviral medications are available to treat influenza, and over-the-counter medications can help alleviate symptoms.

How long does Influenza last?
The duration of influenza typically ranges from a few days to less than two weeks, but fatigue and cough may persist.

Can Influenza lead to other health problems?
Influenza can lead to complications such as pneumonia, bronchitis, sinus and ear infections, and worsening of chronic conditions like heart disease and diabetes.

When should someone with Influenza seek medical attention?
Individuals should seek medical attention if they experience difficulty breathing, chest pain, severe headache, or if their symptoms worsen over time.

Can Influenza be diagnosed without a test?
While a diagnosis can often be made based on symptoms and physical examination, laboratory tests may be necessary to confirm the presence of influenza virus.

Article last updated on: 18th October 2025.
If you have any feedback, please get in touch.

See more

 Conditions  Symptoms  Procedures

Diagnosis Pad
Medical AI Assistant with Differentials, Guidance, Transcriptions, Notes, Medical Encyclopedia and Explainable AI.
Download from App Store Download from Google Play
Available for iOS, macOS and Android.

Medical Disclaimer

The information provided is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read on this site. We we do not guarantee, and assume no legal liability or responsibility for the accuracy, currency, or completeness of the information provided.