Can eating leftover rice make you severely ill? Here’s what to know

Often referred to as "reheated rice syndrome," this condition stems from food poisoning caused by Bacillus cereus.

While many diligently steer clear of raw chicken and unrefrigerated mayonnaise to stave off food poisoning, there may be the unexpected culprit lurking in one’s kitchen — leftover rice.

Often referred to as “reheated rice syndrome,” this condition stems from food poisoning caused by Bacillus cereus, a bacterium that poses a risk when cooked food is left at room temperature for extended periods. If ingested the bacteria can cause bouts of vomiting and diarrhea, and in the rare instance, death, experts warn.

“This is a heat-tolerant bacterium, it will grow at higher temperatures,” Jason Tetro, a microbiologist based in Edmonton and specialist in emerging pathogens, told Global News. 

This means that even if you cook your rice, the bacteria can still survive.

“The reason that it is a concern is because certain types of Bacillus cereus can create a toxin. There are two types of toxins, one makes it come out the other way (diarrhea). The second makes it come out through the mouth, both of which are very unhappy and make you feel very unwell,” he said. “And in approximately a handful of cases all over the world, over the last 35 to 40 years, we’ve seen a few deaths.“

Bacillus cereus is found in all environments. While rice often takes the blame, pasta, cooked vegetables and meats are also susceptible to contamination.

While this food-borne illness isn’t a new phenomenon, it’s recently been making waves on social media after a decades-old news story resurfaced on TikTok. Microbiologists are sounding the alarm, using platforms like TikTok to remind people about the importance of cooking and storing foods like rice and pasta properly.

Originally published in 2011 in the Journal of Clinical Microbiology, the case report said in 2008 a 20-year-old from Belgium became sick and died after eating a meal of leftovers of spaghetti with tomato sauce, which had been prepared five days before and left in the kitchen at room temperature.