A person remains contagious with a cold as long as she has symptoms, according to Healthline. The viruses that cause colds can spread easily through either the respiratory system or through physical contact.
If a person has a cold and chooses to go out, she should take precautions to ensure the cold is not spread to others, such as covering her mouth when coughing and sneezing, according to Healthline. Most viruses spread through the respiratory system via coughs and sneezes. If a tissue is unavailable, a person should cough or sneeze into her elbow. Additionally, a person should avoid direct contact with others as much as possible and wash her hands frequently.