Symptoms of Swine Flu

Swine flu is caused by a variant strain of influenza virus. It is termed H1N1 2009 after the 2009 pandemic in which it caused infection millions worldwide.

swine fluImage Credit: cliplab /

Swine flu symptoms

According to the Robert Koch Institute (RKI) the symptoms of swine flu are similar to other influenza infections.

It causes infection and inflammation of the upper airways.

There may be at least 2 symptoms among the following list in a person infected with a flu virus:

  • Sudden, high fever usually accompanied by chills and shivering. Fever is usually above 38ºC.
  • Sneezing, runny nose and watering red eyes
  • Coughing
  • Headaches
  • Body and limb aches and muscle pains
  • Coughing
  • Loss of appetite
  • Tiredness
  • Chest congestion
  • Sore throat
  • Nausea and vomiting
  • Diarrhoea. A stomach upset is a particular feature of the H1N1 2009 virus infection
  • In severe cases there may be difficulty breathing
  • The illness typically lasts for 4 days to a week. The patient is capable of transmitting the infection 1 day prior to the onset of symptoms to 7 days after onset.
  • Children may also develop severe disease with difficulty breathing, rapid and shallow breathing, bluish discoloration due to lack of oxygen (cyanosis), confusion, delirium, irritability, refusal of food, dehydration etc.

High risk groups

Most swine flu infections are mild and resolve by themselves. However, in the high risk groups there is a risk of complications. High risk groups include:

  • Pregnant women
  • Those with chronic respiratory disease like asthma or Chronic Obstructive Pulmonary Disease (COPD)
  • Chronic heart disease like chronic heart failure
  • Chronic kidney disease
  • Long term liver disease
  • Neurological conditions like Parkinson's disease, Alzheimer’s disease etc.
  • Those with suppressed immunity like AIDS sufferers, people who have received organ transplants and are on immunosuppressant drugs etc.
  • Those with diabetes mellitus
  • Infants and toddlers
  • The elderly over 65 years of age

How is swine flu spread?

Swine flu is not spread through eating properly handled and prepared pork or other produce from pigs.

The virus can be directly transmitted from pigs to people and from people to pigs. This is common among people who are in close proximity to infected pigs, such as those working with them. Human-to-human transmission then occurs and the virus spreads. This transmission occurs from the infected person coughing or sneezing into the air breathed by healthy persons.

People also may become infected by touching objects with the flu virus on them and then touching their mouth or nose. This could be a door knob, public phone or computers, etc.


Further Reading

Last Updated: Nov 4, 2022

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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