Prevention of the common cold:

The best way to avoid a cold is to avoid close contact with existing sufferers, to thoroughly wash hands regularly, and to avoid touching the face. Handwashing is the simplest and most effective way to keep from getting rhinovirus colds. Not touching the nose or eyes is another. Individuals with colds should always sneeze or cough into a facial tissue, and promptly throw it away. If possible, one should avoid close, prolonged exposure to persons who have colds. Sneezing and coughing should  be done into tissues, which should then be carefully disposed of. When possible, the sick person should sleep in a separate room. People who are coughing or sneezing from a cold should not go to work or school where they might infect others. Cleaning shared objects and surfaces can also help to reduce the spread of common cold viruses.

The development of a vaccine that could prevent the common cold has reached an impasse because of the discovery of many different cold viruses. Each virus carries its own specific antigens, substances that induce the formation of specific protective proteins (antibodies) produced by the body. Until ways are found to combine many viral antigens in one vaccine, or take advantage of the antigenic cross-relationships that exist, prospects for a vaccine are dim. Evidence that changes occur in common-cold virus antigens further complicate development of a vaccine. Such changes occur in some influenza antigens and make it necessary to alter the influenza vaccine each year.

Different studies have found that large doses of vitamin C reduce the duration of a cold by a range of 5% to 50%. Echinacea and high-dose vitamin C (up to 2,000 milligrams per day) have not been shown to prevent colds. When sprayed into the nose, the substance interferon reduces the chance of acquiring a rhinovirus cold. However, interferon causes irritation and bleeding of the nose and does not work against other cold viruses. Interferon nasal spray is not commercially available in the United States.