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Colds

What Is a Cold?

A common cold is defined as an upper respiratory infection caused by a virus that usually affects the nose but may also affect the throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes -- but not the lungs. Statistically, the cold is the most commonly occurring illness in the entire world. The common cold is a self-limiting illness caused by any one of more than 250 viruses. However, the most common causes of colds are rhinoviruses. Colds may also be termed coryza, nasopharyngitis, rhinopharyngitis, and sniffles. Everyone is susceptible to colds.

The common cold produces mild symptoms (see below) usually lasting only five to 10 days, although some symptoms may last for up to three weeks. In contrast, the "flu" (influenza), which is caused by a different class of virus, can cause severe symptoms but initially may mimic a cold.

What Causes Colds?

Viruses cause colds. Most cold-causing viruses are very contagious and are transmitted from person to person. Some facts about common colds are as follows:

  • Although colds have been with humans likely for eons, the first common cold virus was identified in 1956 in England, so the history of the cause of colds is relatively recent.
  • Of the viruses that cause a cold, the most commonly occurring subtype is a group that lives in the nasal passages known as the "rhinovirus." Other less common cold viruses include coronavirus, adenovirus, and respiratory syncytial virus (RSV).
  • Cold viruses may spread through the air and can be transmitted from airborne droplets expelled when someone with a cold coughs or sneezes. Close association with an infected person with a cold is the major risk factor.
  • The primary means of spreading a cold is through hand-to-face or -mouth contact or from objects that have been touched by someone with a cold, or by touching items where droplets produced by coughs or sneezes have recently landed and then touching the face or mouth.
    • The typical transmission occurs when a cold sufferer rubs his or her nose and then, shortly thereafter, touches or shakes hands with someone who, in turn, touches his or her own nose, mouth, or eyes.
    • Virus transmission also often occurs via frequently shared or touched objects such as doorknobs and other hard surfaces, handrails, grocery carts, telephones, and computer keyboards.
Medically Reviewed by a Doctor on 8/31/2016

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Patient Comments & Reviews

The eMedicineHealth doctors ask about Colds:

Common Cold - Symptoms

What symptoms did you experience with your cold?

Common Cold - Home Remedy

What home remedy did you use on your colds?

10 Common Cold Prevention Tips

1. Wash your hands often.

Washing your hands for at least 20 seconds can help protect you from getting sick. Washing your hands frequently helps prevent the spread of infection. Use plain soap and water, making sure to pay attention to spaces between fingers, and under the fingernails. Rinse and dry with a clean towel. Teach your children to wash their hands properly. If soap and water is unavailable, alcohol-based hand sanitizers are an alternative.


Read What Your Physician is Reading on Medscape

Rhinoviruses »

The common cold is an acute respiratory tract infection (ARTI) characterized by mild coryzal symptoms, rhinorrhea, nasal obstruction, and sneezing.

Read More on Medscape Reference »


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