Is the 5-Second Rule True?

We’ve all done it. Dropped a snack, a meal, an ingredient we were planning to eat, quickly picked it up, and declared the “five-second rule.” The food hasn’t been on the floor that long! It barely touched the ground, really! Your reflexes are faster than any cooties. Right? 

Well, bad news for clumsy cooks: food that falls on the ground isn’t safely edible, according to experts. The five-second rule is an urban legend and one that can potentially lead to severe stomach pain, or worse.  

“Unfortunately the five-second rule is a myth,” confirms Wendi Lebrett, MD, board-certified internal medicine physician and gastroenterology fellow. “There is no recommended safe time for food to be consumed when it has dropped on the floor.”

You wouldn’t lick your finger after touching it to the floor for five seconds (or less!) and that same reasoning applies to food. “Bacteria can transfer to food almost immediately upon contact,” says Kenneth Brown, MD. Whether that food is a sticky piece of pasta that attracts dirt or a dry cracker that you can pick up spotless doesn’t really matter.

“Factors such as the type of food, surface, and existing microorganisms influence contamination risk, not just time,” says Dr. Brown. “While the rule might offer a quick solution, microbial science shows food safety is more complex.” Research published in the Journal of Applied Microbiology shows that salmonella can contaminate common foods like bread and bologna very quickly, within five seconds. “This speedy attachment is due to bacterial structures named fimbriae and pili, which act like biological hooks, making contact with and adhering to the food’s surface rapidly,” explains Dr. Brown. 

Oddly enough, clean-looking surfaces may be the worst culprits when it comes to transferring bacteria for formerly edible food. In 2016, Rutgers University researchers debunked the five-second rule. Researchers tested four different foods (watermelon, bread, bread with butter, and gummy candy) on four different intentionally contaminated surfaces (stainless steel, ceramic tile, wood, and carpet) for various periods of time, as briefly as one second and five seconds. Results found that wetter foods, like watermelon, showed the highest risk of bacterial transfer, and carpet had much lower contamination transfer rates than tile and stainless steel, which is kind of gross when you think about how much bacteria a carpet can soak up before the food gets to it. The study concluded that longer contact time allows for more bacterial transfer, but five seconds is more than enough time for that crisp baguette spread with luscious butter to potentially carry salmonella. To the compost bin!  

While we can’t go through life assuming every surface we touch or drop food on contains harmful bacteria, the risk of infection isn’t really worth taking. “Bacteria can transfer onto food the instant it has made contact,” emphasizes Dr. Lebrett. “The primary concern is the risk of contracting a gastrointestinal infection from bacteria transfer onto the food.”

And that infection can be very unpleasant. “The spectrum of symptoms can be quite broad, from a minor upset stomach to something much more intense, like severe dehydration or widespread infections that affect more than just the digestive system,” says Dr. Brown. “It’s a bit like when a small error in a complex machine throws the whole system off balance.” Salmonella, E. coli, and Listeria could all be on your dropped food, pathogens Dr. Brown likens to unwelcome guests at a dinner party — each with the potential to ruin the evening in unpredictable and unwanted ways. You wouldn’t eat a meal your horrible ex cooked, and the same should apply to that once delicious food, now on the ground.  

Sure, you’ve dropped food, picked it up, consumed it, and felt perfectly fine. That may be good luck or due to a strong immune system. But still, every dropped piece of food is a risk to put in your mouth. Instead of the five-second rule, perhaps replace that edict with advice from Dr. Brown. “Avoid eating anything that has fallen on the floor, regardless of how quickly it is picked up.”