Influenza (Flu): Symptoms, Causes, Diagnosis & Treatment

Influenza, usually known as the flu, is an infectious disease caused by the influenza virus. Symptoms can be mild to severe including high fever, runny nose, sore throat, muscle pains, headache, coughing, sneezing, and feeling tired. These symptoms usually begin two days after the exposure to the virus and last for less than a week. In children, diarrhea and vomiting may occur, but these are not common in adults.

There are three types of influenza virus that affect people; Type A, Type B, and Type C. The virus is spread through the air from coughs or sneezes mostly over relatively short distances. It can also be spread by touching contaminated surfaces and then touching the mouth or eyes.

The infection may be confirmed by testing the throat, sputum, or nose, for the virus. However, people may still have an infection even if the results are negative. Polymerase chain reaction detects the virus’ RNA and is accurate in testing for the virus.

Annual vaccinations against influenza are recommended for those at high risk. Vaccine made for a year may not be useful in the following year, since the virus evolves rapidly. Antiviral drugs have been used to treat influenza.

About 20% and 10% of unvaccinated children and adults respectively are infected each year, and mostly the young, the old and those with other health problems succumb to death. Outbreaks can occur at any time of the year in areas around the equator. About three to five million cases of severe illness and about 250,000 to 500,000 deaths occur every year globally because of the influenza virus.

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How Does Influenza Affect Your Body?

The first effect of influenza (flu) on the body is a fever with chills, muscle aches, a feeling of general weakness, fatigue, and a headache. Influenza virus infects the respiratory system. As a result, effects on the body often appear on the throat, nose, and lungs. The nose may become congested or runny, the cough may move from dry to wet, and the throat may become sore as the virus runs its course. Sometimes, the flu may lead to pneumonia, which can be serious.

What Are The Causes of Influenza?

  • The virus can spread through air droplets when an infected person coughs or sneezes. It can also spread when one comes into contact with contaminated objects.
  • A person may be infectious both, before and during the time they show symptoms.
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What Are The Risk Factors of Influenza (Flu)?

  • Age – Seasonal influenza can infect young children and older adults.
  • Surrounding area – People living and working in nursing homes or military barracks are more likely to develop influenza.
  • Weakened immune system – Cancer treatments, anti-rejection drugs, corticosteroids, and HIV/AIDS can weaken the immune system making it easier to catch influenza.
  • Chronic illnesses – Asthma, diabetes, or heart problems may increase your risk of influenza complications.
  • Pregnancy – Pregnant women are more likely to develop influenza, particularly in their second and third trimesters.
  • Obesity – People with a BMI of 40 or more have an increased risk of complications from the flu.
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What Are The Symptoms of Influenza (Flu)?

Symptoms of influenza (flu) can start suddenly one to two days after infection. Usually, the first signs are chills and body aches, with body temperatures ranging from 38 to 39 °C.

Symptoms of influenza:

  • Fever and chills
  • Coughing
  • Nasal congestion
  • A runny nose
  • Sneezing
  • A sore throat
  • Hoarseness
  • Earache
  • Muscle pains
  • Fatigue
  • A headache
  • Irritated, watering eyes
  • Reddened eyes, skin, mouth, throat, and nose
  • Rash

In children, gastrointestinal symptoms such as vomiting, diarrhea, and abdominal pain may occur especially in the case of influenza B.

It is usually difficult to distinguish between common cold and influenza’s symptoms during early stages.

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How is Influenza Diagnosed?

Rapid Molecular Assay (RMA) – In this flu test, an upper respiratory tract specimen (mucus) is taken using a nasal swab or a nasopharyngeal swab. This test is usually done within 3–4 days of symptom onset, as upper respiratory viral shedding takes a downward spiral after that.

How to Prevent And Control Influenza?

  • It is recommended that everyone aged 6 years or older should get an annual flu vaccination.
  • Most of the flu vaccines contain egg protein. Those who are allergic to egg must alert their doctors about the same.
  • Wash hands frequently to prevent many common infections.
  • Use alcohol-based hand sanitizers if soap and water are not readily available.
  • Cover the mouth and nose while coughing or sneezing, and avoid contaminating using a tissue.
  • Avoid crowded areas especially during the flu season.

Treatment of Influenza – Allopathic Treatment


  • Antiviral medication – This reduces the virus’ ability to replicate, thus preventing serious complications such as neuraminidase inhibitors (oseltamivir, zanamivir, laninamivir, and peramivir) and M2 protein inhibitors (adamantane derivatives).
  • Decongestant – This medication relieves nasal congestion, swelling, and runny nose.
  • Cough medicine – A cough medication blocks the cough reflex and may also thin and loosen mucus, making it easier to clear from the airways.
  • Nonsteroidal anti-inflammatory drug – These are given to relieve pain, decrease inflammation and reduce fever.
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Treatment of Influenza – Homeopathic Treatment

  • Aconite – This medicine is taken to prevent congestion once the cold starts to affect the patient. It can also be used when tingling and burning sensations in the nose start.
  • Arsenicum – This medicine helps in treating congestion and severe cold.
  • Allium Cepa – Persistent discharge from the nose is one of the symptoms for which this medicine is usually prescribed.
  • Euphrasia – This medication is prescribed when a part of the respiratory mucous membrane is affected.
  • Mercurius – This medicine can be prescribed to treat frontal sinuses that may be a suffering due to the flu.

Influenza – Lifestyle Tips

  • Drink plenty of liquids to stay hydrated.
  • Get enough rest and proper sleep.
  • Use over-the-counter pain relievers if the pain is severe.

What Are The Recommended Exercises For a Person With Influenza?

The following exercises are recommended for a person with Influenza (Flu):

  • Walking
  • Swimming
  • Biking
  • Running

Influenza & Pregnancy – Things to Know

  • Women in and after the second trimester (especially those in the third trimester) are at a higher risk of influenza-related complications.
  • Pregnant women who have chronic medical conditions are also at a higher risk of serious influenza complications and should be immunized.
  • Flu can be life-threatening for pregnant women and their babies.
  • Flu shots are safe for both the mother and the baby and can be given at any stage of the pregnancy.

Common Complications Related to Influenza (Flu)

  • Pneumonia
  • Bronchitis
  • Asthma flare-ups
  • Heart problems
  • Ear infections


Q. Why should I get vaccinated against influenza?

A. Vaccination is the only best way to help prevent yourself from getting influenza (flu).

Q. How do influenza vaccines work?

A. After two weeks of getting a vaccination, the body starts developing antibodies which provide protection against infection with the viruses that are in the vaccine.

Q. Why do I need an influenza vaccine every year?

A. You need an influenza vaccine every year because the influenza virus continually evolves and the protection from the previous vaccination declines over time.

Q. Can influenza vaccines give me influenza?

A. The inactivated flu shot cannot give one influenza. Influenza vaccine contains killed influenza viruses that cannot cause infection.

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