What is influenza (flu)?
The flu is a respiratory infection caused by a virus (germ). Influenza occurs most often during the winter and easily spreads from person to person. The "flu season" in the Northern hemisphere runs from October to May and usually peaks between December and February.
Most people who get influenza feel sick for a week or two and recover. In some people, the flu leads to more serious lung infections or to worsening of underlying conditions, such as heart failure or emphysema.
What are the symptoms of influenza (flu)?
- Sudden onset of moderate to high fever.
- Dry cough.
- Sore throat.
- Runny nose.
- Loss of appetite.
- Muscle aches.
How can you tell the difference between a common cold and influenza (flu)?
Many cold and flu symptoms are similar. Both the common cold and the flu are caused by viruses.
There are some differences with influenza. Symptoms of influenza often hit suddenly and cause you to become weaker and weaker. While the more uncomfortable symptoms of flu generally last from three to seven days, the dry cough and fatigue of influenza can last two to three weeks. Signs that influenza is getting worse include increasing degree of fever, and shortness of breath. If you think that your illness is getting worse, contact your doctor right away.
Symptoms of colds and flu
|Fever||Adults-rare; children-sometimes||High fever (100°F up to 104°F in adults and 106°F in children); can last 3 to 4 days)|
|Runny nose||Common (Nasal discharge may have a yellow- or green-colored tint. This does not mean you have a bacterial infection.)||Sometimes|
|Headache||Sometimes (usually mild)||Common (usually severe)|
|Body aches and pains||Sometimes (usually mild)||Common (can be severe)|
|Fatigue (tiredness), weakness||Sometimes (usually mild)||Common (can last up to 2-3 weeks)|
|Chills, sweating||Not common||Common|
|Nausea||Uncommon||Common in children|
|Loss of appetite||Sometimes||Common|
|Cough||Common (mild to moderate)||Common (can be intense, severe)|
|Chest congestion, discomfort||Common (mild to moderate)||Common (can be severe)|
|Vomiting||Not common||Sometimes (more in children)|
|Diarrhea||Not common||Sometimes (more in children)|
|Complications||Sinus congestion, earache||Bronchitis, pneumonia (can be life-threatening)|