Getting out the door in the morning to start your daily grind can be a bit difficult minus caffeine. So you grab that coffee mug that’s been in the sink since yesterday … or the day before … or was it the day before that? Without thinking you briskly rinse it with water and pour a fresh mug of java. Five minutes later when the coffee has kicked in and you are stuck in unenviable traffic you ask yourself, “Should I have used dish detergent?”
It’s actually not really necessary, infectious disease expert Jeffrey Starke, MD, from Baylor College of Medicine, told scienceofus.com. “If I went and cultured the average unwashed coffee cup, of course I’m going to find germs,” he said. “But remember the vast majority came from the person who used the cup.”
Since you don’t generally contract the same cold virus that you’ve had in the past because you have already built up immunity to it, you’re in the clear (but not if you decide to share your mug). In other words you are unable to reinfect yourself because you have built up the antibodies to that particular germ.
Starke does issue some warnings though. First if you use milk, creamer, or sugar with your coffee or tea and they are left in the mug overnight or longer, there is a chance mold can grow. And when you do clean your mug, use a clean kitchen sponge! Kitchen sponges are notorious germ magnets. Here’s how to properly clean your sponge to banish germs.
MORE: Here’s the spill-proof way to carry your coffee mug, according to science.