Touching fridge door handles, door knobs or the television remote control could leave you with a cold.
Scientists at the University of Virginia said cold sufferers often leave their germs on a host of household surfaces, where they can live for two days or longer.
The university, known for its virology research, tested surfaces in the homes of people with colds and reported the results at the nation's premier conference on infectious diseases.
For the study, researchers started with 30 adults showing early symptoms of colds. They were asked to name 10 places in their homes they had touched in the preceding 18 hours, and researchers used DNA tests to hunt for the cold germ rhinovirus.
Dr Birgit Winther, an ear, nose and throat specialist who helped conduct the study, said: "We found that commonly touched areas like fridge doors and handles were positive about 40% of the time."
Next, the researchers deliberately contaminated surfaces with participants' mucus and then tested to see whether the germs stuck to their fingers when they did common tasks. More than half of the participants got the virus on their fingertips 48 hours after the mucus was smeared.