Influenza, a cold, and stomach upset are different illnessesThe chart below shows the differences between influenza, a cold and a stomach upset.
|Type of infection||Respiratory infection||
|Description / symptoms||
|Virus involved||Influenza A or B||Many different kinds of viruses such as rhinovirus, coronavirus, adenovirus, etc.||Norovirus (Norwalk-like viruses) is the most common.|
|Fever||Usually high, beginning suddenly and lasting 3–4 days.||Sometimes||Rarely|
|Headache||Usually, can be severe.||Rarely||Sometimes|
|Chills, aches, pain||Usually, and often severe.||Rarely||Common|
|Loss of appetite||Sometimes.||Sometimes||Frequently – usually nausea, vomiting and diarrhea occur as well.|
|Sniffles or sneezes||Sometimes||Usually||Rarely|
|Extreme tiredness||Usually – tiredness may last 2–3 weeks or more.||Rarely||Sometimes|
|Involves whole body||Usually||Never||Stomach and bowel only.|
|Symptoms appear quickly||Yes||More gradual||Yes|
|Pneumonia, kidney failure, swelling of the brain and death.||Sinus infection or ear infection.||Dehydration (losing more fluid than you take in).|
|Vaccine||Yearly vaccine provides protection against two influenza A strains and one influenza B strain.||No vaccine available.||No vaccine available.|
* Note: A stomach upset is sometimes incorrectly called the "stomach flu" – there is no such illness as "stomach flu." As noted in the chart, stomach upsets are caused by viruses and other micro-organisms but not by the influenza virus.