• Lung Care Foundation
  • 011 - 4225 2328
  • lung@lcf.org.in

What is influenza?

Influenza, or flu, is a serious respiratory illness that is easily spread from person to person. It is caused by the influenza virus which can infect the nose, throat, and lungs. The viruses pass through the air and can enter your body through your nose or mouth. It can also be acquired from contaminated surfaces. It can cause mild to severe illness, but in some cases, can become more serious, leading to hospitalization or death.


There are three different influenza virus fami¬lies: A, B, and C.

  • Influenza Type A viruses can infect people, as well as birds, pigs, horses, and other animals. There are different strains (or subtypes) of influenza type A viruses, two of which circulate among humans: H1N1 and H3N2.
  • Influenza Type B viruses are usually found only in humans. Influenza B viruses can cause illness among humans, but in general, are associated with less severe infection than influenza A viruses.
  • Influenza Type C viruses cause mild illness in humans. Influenza C cases occur much less frequently than A and B

The viruses change constantly and different strains circulate around the world every year.

These viruses spread when people with a flu cough, sneeze or talk, sending droplets with the virus into the air and potentially into the mouths or noses of people who are nearby. You can also get flu by touching a surface or object that has flu virus on it and then touching your own mouth, eyes or nose.


Flu symptoms often appear suddenly and can include:

  • Sudden onset of high fever
  • A headache, muscle aches, and joint pain
  • A cough (usually dry)
  • Chills
  • A sore throat
  • Nasal congestion and runny nose
  • Fatigue
  • Stomach symptoms such as nausea, vomiting or diarrhea may occur but are more common in children than adults.


Due to the non-specific nature of flu symptoms, it is difficult to tell if you have the flu based on symptoms alone. If you are at high risk for complications, a doctor’s exam may be needed to tell whether you have developed the flu or a complication of the flu. There are tests that can determine if you have the flu as long you are tested within the first 2 or 3 days of illness.


Treating the flu is mainly non-pharmacological and includes staying home, getting adequate rest and staying hydrated. Your doctor may prescribe antiviral medication to treat the virus, and over-the-counter medication can be used to minimize discomfort associated with flu symptoms (for example, decongestant and antihistamine for congestion, cough and nasal discharge). Antibiotics are not useful in treating the flu but may be prescribed if necessary to clear up a related sinus or ear infection.

There are two commonly used antiviral drugs: oseltamivir (trade name Tamiflu®), which comes in pill form, and peramivir (trade name Rapivab®), which is administered intravenously. These drugs have been shown to reduce flu symptoms if started within a day or two of getting sick.

Treatment with antiviral medicine is most important for people with suspected or confirmed influenza who are at higher risk for complications, including:

  • Children younger than 2 years old
  • Adults 65 years and older
  • Pregnant women
  • People with certain chronic medical conditions, such as asthma or COPD, or with suppressed immune systems


Get the flu shot every year.
The flu shot is your best defense against the flu. It’s recommended for most people over six months old, and especially recommended for people in high-risk groups:

  • Seniors
  • Children
  • Childcare workers
  • Health-care workers
  • People with weak immune systems
  • People with chronic (long-term) diseases like asthma and COPD
  • Pregnant women

Stop the spread of germs.
Wash your hands properly and often. The most common way to catch the flu is through your hand. If you touch something with flu germs on it, then touch your eyes, nose or mouth, you could get infected with the flu.
Stay away when you are sick or from others when they are sick.
Don’t spread the flu. We highly recommend that you stay home from work, school and public places when you are sick. Cover your mouth and nose with a tissue or your elbow when coughing or sneezing.