Related concepts:

Influenza

Introduction to the flu:

For many people, cold and flu have become an inseparable pair, like salt and pepper or New Year's and weight loss. Walking down the "cold and flu" aisle of any drugstore, you will find stacks of bright boxes with bold claims of help for those suffering from a cold or the flu. Since the two illnesses share some similar symptoms, and both come during "cold and flu season," the two often run together in people's minds. We have a vague idea that they are different, but if pressed, have a hard time saying exactly how. The cold is much more common. The flu is much more serious.

What is the flu?

A single family of viruses – the influenza viruses – causes the flu.

Unlike with the common cold, both adults and children with the flu generally have a fever and feel sick all over. For the great majority of people, the illness is quite unpleasant but not dangerous.

However, the flu can be quite a serious illness. The most deadly recent worldwide outbreak was the flu epidemic at the beginning of the 20th century, which killed more than 20 million people.

Even today, more than 20,000 people in the United Sates die from the flu each year. This number is a small percentage of those who get the flu (much less than one percent). They are primarily those who are weak from advanced age or a major illness.

Still, about one percent of otherwise healthy children get sick enough from the flu to be hospitalized.

Who gets the flu?

Most people get the flu once every year or two or three – unless they are vaccinated. It can happen at any age, but is most common among school-aged children.

The flu is most common during the winter months.

What are the symptoms of the flu?

The flu can take many forms. It is not, primarily, a “tummy flu.”

Classically, the flu begins abruptly, with a fever in the 102 to 106 degree range, a flushed face, body aches, and marked lack of energy. Some people have other systemic symptoms such as dizziness or vomiting. The fever usually lasts for a day or two, but can last five days.

Somewhere between day 2 and day 4 of the illness, the "whole body" symptoms begin to subside, and respiratory symptoms begin to increase. The virus can settle anywhere in the respiratory tract, producing symptoms of a cold, croup, sore throat, bronchiolitis, ear infection, and/or pneumonia.

The most prominent of the respiratory symptoms is usually a dry, hacking cough. Most people also develop a sore (red) throat and a headache. Nasal discharge and sneezing are not uncommon.

The initial symptoms of inhalational anthrax can be similar to those of the flu.

Is the flu contagious?

The flu is very contagious.