Staying home sick when you're actually sick is no fun for anyone, but knowledge that you are still a hulking heap of virulent plague is arguably worse. Wondering if you are or aren't contagious can throw off your relationships, screw with your best-laid plans, and turn your illness into a table tennis match if you happen to live with a roommate.
Luckily, science has mostly figured out how to cure a cold, as well as how long you need to worry about it after you've gotten rid of it.
How long is a cold contagious?
Most experts agree that a cold is contagious before you even start showing symptoms, and can increase in virulence with the severity of symptoms. It usually takes 24 to 72 hours for your cold to develop into a flaring-nostril, rivers-of-snot levels of bad. A common cold is most contagious in the first two to three days of infection, and typically not contagious after a week. By then your symptoms have probably subsided.