Q: I’m prone to cold sores. Do I need to replace my toothbrush and lipsticks every time a blister appears?

A: No, that’s not necessary — because the reappearance of a cold sore does not mean that you have somehow “reinfected” yourself through contact with a contaminated object. Cold sores are caused by an infection with the herpes simplex virus, and once you catch the virus, you have it forever. Most of the time, the virus lies dormant in nerves in the skin… but when the virus is reactivated by some type of stimulus (such as fever, illness, sunburn or stress), the blisters reappear.

As for infecting others, the virus generally is transmitted via direct person-to-person contact — and this can occur even when no blisters are present, due to what is called asymptomatic viral shedding. But you do not need to worry about infecting someone else with your toothbrush or lipstick because the virus particles do not live for very long off the body. We have no routine recommendations for disinfecting objects because transmission from an object such as a toothbrush or lipstick would be rare.