What causes colds and the flu?

Colds

The common cold is an acute, self-limited viral infection of the nose, throat, and sinuses. It is usually caused by a rhinovirus, but other viruses can also cause the cold. Rhinoviruses are spread through the air when an infected person coughs or sneezes. They can also be spread through contact with contaminated objects, such as doorknobs or toys.

The incubation period for the common cold is typically 2-3 days. Symptoms of the common cold include:

* Nasal congestion or a runny nose

* Sneezing

* A sore throat

* A cough

* Headaches

* Muscle aches

* Fatigue

* A fever (in some cases)

Flu

The flu, or influenza, is a more severe respiratory illness than the common cold. It is also caused by a virus, but the flu virus is different from the rhinovirus that causes the cold. The flu virus is spread through the air when an infected person coughs or sneezes. It can also be spread through contact with contaminated objects.

The incubation period for the flu is typically 1-4 days. Symptoms of the flu include:

* A high fever (101 degrees Fahrenheit or higher)

* Chills

* Body aches

* A headache

* Fatigue

* Weakness

* A loss of appetite

* A runny nose

* A sore throat

* A cough

* Vomiting and diarrhea (in some cases)

The flu can be a serious illness, especially for the elderly, the very young, and people with chronic medical conditions. In severe cases, the flu can lead to hospitalization and even death.