Sat. Apr 13th, 2024

What happens to your body when you have flu?

Influenza A and B are the ones most commonly associated with seasonal flu outbreaks in humans.

Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. It typically manifests with symptoms such as fever, cough, sore throat, muscle aches, fatigue, and sometimes nasal congestion.

The flu can range from mild to severe and can lead to complications, especially in vulnerable populations such as the elderly, young children, pregnant women, and individuals with underlying health conditions. It spreads through respiratory droplets when an infected person coughs, sneezes, or talks, and can also be transmitted by touching surfaces contaminated with the virus.

Vaccination is the most effective way to prevent the flu, along with practicing good hygiene habits like frequent handwashing and avoiding close contact with sick individuals. Treatment often involves rest, hydration, and sometimes antiviral medications, particularly if administered early in the course of the illness.


There are four main types of influenza viruses: influenza A, B, C, and D.

  1. Influenza A: This type is the most common and can infect humans as well as other animals like birds and pigs. Influenza A viruses are further classified based on the variations in two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). These variations give rise to different strains, such as H1N1 or H3N2, which can cause seasonal flu outbreaks in humans.
  2. Influenza B: This type primarily affects humans and is less common than influenza A. Influenza B viruses do not have subtypes but can still cause seasonal outbreaks.
  3. Influenza C: Unlike types A and B, influenza C viruses typically cause milder respiratory infections and are less common. They do not cause widespread seasonal outbreaks like influenza A and B viruses.
  4. Influenza D: This type mainly affects cattle and is not known to infect humans frequently. Influenza D viruses have been identified more recently and are not considered to be a significant public health threat to humans at this time.

Among these types, influenza A and B are the ones most commonly associated with seasonal flu outbreaks in humans.

Bodily changes

When you have the flu, your body undergoes several changes both before and after the onset of symptoms:

Prior to Symptoms:

  1. Incubation Period: After exposure to the flu virus, there is an incubation period ranging from 1 to 4 days before symptoms typically appear. During this time, the virus begins to replicate in your body, but you may not yet feel unwell.

After Symptoms Appear:

  1. Immune Response: Your immune system recognizes the presence of the virus and begins to mount a defence. White blood cells, particularly T cells and B cells, are activated to fight off the infection.
  2. Symptoms Onset: Common flu symptoms begin to manifest, including fever, chills, cough, sore throat, runny or stuffy nose, muscle or body aches, fatigue, and sometimes vomiting or diarrhoea. These symptoms can vary in severity depending on the individual and the strain of the flu virus.
  3. Inflammation: The immune response triggers inflammation in the respiratory tract and throughout the body, leading to symptoms such as congestion, sore throat, and muscle aches.
  4. Viral Replication: The flu virus continues to replicate in the body, particularly in the respiratory tract, which contributes to the spread of the infection and the duration of symptoms.
  5. Complications: In some cases, the flu can lead to complications such as pneumonia, bronchitis, sinus infections, ear infections, or worsening of underlying health conditions. These complications are more common in vulnerable populations such as the elderly, young children, pregnant women, and individuals with weakened immune systems.

After Recovery:

  1. Resolution of Symptoms: With proper rest, hydration, and treatment, most people recover from the flu within 1 to 2 weeks. Symptoms gradually subside as the immune system clears the virus from the body.
  2. Recovery Period: Even after the symptoms have resolved, it may take some time for the body to fully recover its strength and energy levels.
  3. Immunity: Following recovery from the flu, your immune system develops antibodies specific to the virus, providing some level of immunity against future infections with the same or similar strains of the flu virus. However, immunity may not be long-lasting, as the flu virus can mutate over time, requiring annual vaccination to maintain protection.


Recovering from the flu typically involves a combination of self-care measures and, in some cases, medical treatment.

Here are some steps you can take to help your body recover from the flu:

  1. Rest: Get plenty of rest to allow your body to focus its energy on fighting off the infection. Avoid strenuous activities and prioritize sleep to help your body heal.
  2. Stay Hydrated: Drink plenty of fluids such as water, herbal tea, clear broths, or electrolyte-rich beverages to prevent dehydration, especially if you have a fever or are experiencing vomiting or diarrhea.
  3. Manage Symptoms: Take over-the-counter medications to alleviate symptoms such as fever, headache, muscle aches, and congestion. Acetaminophen or ibuprofen can help reduce fever and relieve pain, while decongestants or antihistamines may help with nasal congestion and runny nose. Be sure to follow the recommended dosage instructions and consult a healthcare professional if you have any questions or concerns.
  4. Gargle with Saltwater: If you have a sore throat, gargling with warm saltwater can help soothe irritation and reduce inflammation.
  5. Use Humidifiers or Steam: Breathing in moist air from a humidifier or steam from a hot shower can help ease congestion and loosen mucus in the respiratory tract.
  6. Eat Nutritious Foods: Maintain a healthy diet rich in fruits, vegetables, lean proteins, and whole grains to provide your body with essential nutrients and support immune function.
  7. Avoid Tobacco and Alcohol: Refrain from smoking or drinking alcohol, as these can worsen symptoms and hinder the healing process.
  8. Practice Good Hygiene: Wash your hands frequently with soap and water, especially after coughing, sneezing, or blowing your nose, to prevent the spread of the virus to others.
  9. Stay Home: To prevent further transmission of the flu virus, stay home from work, school, and other public places until you have fully recovered and are no longer contagious. Follow the guidelines provided by healthcare professionals or public health authorities.
  10. Seek Medical Attention if Necessary: If your symptoms are severe, persist for more than a few days, or if you have underlying health conditions that may increase your risk of complications, consult a healthcare professional for further evaluation and treatment. Antiviral medications may be prescribed in certain cases, especially if administered early in the course of the illness.


Preventing the flu involves a combination of vaccination, good hygiene practices, and minimizing exposure to the virus.

Here are some key steps to help prevent the flu:

  1. Get Vaccinated: Annual flu vaccination is the most effective way to prevent the flu. The flu vaccine helps your body develop antibodies to protect against the viruses included in the vaccine. It’s recommended for everyone aged 6 months and older, particularly for those at higher risk of complications, such as young children, older adults, pregnant women, and individuals with certain underlying health conditions.
  2. Practice Good Hand Hygiene: Wash your hands frequently with soap and water for at least 20 seconds, especially after coughing, sneezing, blowing your nose, or touching surfaces in public places. If soap and water are not available, use an alcohol-based hand sanitizer.
  3. Cover Your Mouth and Nose: When coughing or sneezing, cover your mouth and nose with a tissue or the inside of your elbow to prevent the spread of respiratory droplets. Dispose of used tissues properly and wash your hands immediately afterward.
  4. Avoid Close Contact with Sick Individuals: Try to avoid close contact with people who are sick with flu-like symptoms, and stay home if you are feeling unwell to prevent spreading the virus to others.
  5. Clean and Disinfect: Regularly clean and disinfect frequently touched surfaces and objects in your home, workplace, and other shared spaces, such as doorknobs, light switches, keyboards, and phones.
  6. Practice Respiratory Etiquette: Encourage others to practice good respiratory etiquette by covering their mouth and nose when coughing or sneezing, and by promptly disposing of used tissues.
  7. Boost Your Immune System: Maintain a healthy lifestyle by eating a balanced diet, staying physically active, getting enough sleep, managing stress, and avoiding smoking and excessive alcohol consumption. A strong immune system can help reduce your risk of getting sick.
  8. Stay Informed: Stay informed about flu activity in your area by monitoring updates from local health departments or the Centers for Disease Control and Prevention (CDC). Follow any recommendations or guidelines provided by public health authorities to help protect yourself and others from the flu.

By following these preventive measures, you can reduce your risk of contracting the flu and help prevent its spread within your community.

By Parvathy Sukumaran

Parvathy Sukumaran is a Content Creator and Editor at JustCare Health. She is an Educator and a Language Lecturer. She holds a Bachelor's Degree in Education and an M.A in English Literature. She is passionate about writing, archaeology, music and cooking.

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