Risk Level: Medium-low.
Gastric juices and saliva do an excellent job of killing off invading germs. But sometimes “these defenses can be overwhelmed,” says Judy A. Daly, Ph.D., director of the microbiology laboratories at the Primary Children’s Medical Center at the University of Utah, in Salt Lake City.

Watch Out For…

Eating Utensils, Lipsticks and Lip Balms, Drinking Glasses, Food: If saliva containing viral germs touches these objects, you could catch a bug, like a stomach virus or a respiratory infection. To be ultrasafe, don’t share. Still, many of us will choose to live dangerously and split a piece of layer cake.

Telephones: After you talk on the phone, germs from your mouth can stay behind for two to three days, allowing respiratory viruses to spread easily. If someone is sick at home, ask him or her to clean the phone receiver after using it. And don’t lend your cell phone if you’re ill.

Toothbrushes: Cold viruses and bacterial infections can linger on toothbrushes for days. And even a small cut in your mouth can create an easy way for germs to enter the body, says Daly. In short, toothbrushes are meant to be personal.