What You Should Know Before Reheating Leftover Rice

You’ve probably done it cooked a big batch of rice, left it on the counter to cool, and reheated it the next day. But that simple move can carry a serious risk. On social media, it’s even been nicknamed “reheated rice syndrome.”

The danger? Food poisoning caused by a heat-resistant bacteria called Bacillus cereus.

Why Leftover Rice Can Make You Sick

Uncooked rice often contains Bacillus cereus, a bacterium that forms spores. These spores survive cooking and can become active once rice sits out at room temperature. And here’s the kicker: reheating rice doesn’t destroy the toxin that the bacteria produce.

“High temperatures can actually wake up the spores,” explains Jennifer J. Quinlan, PhD, food microbiologist at Drexel University.

Once those spores germinate, they create toxins that cause food poisoning symptoms like nausea, vomiting, and diarrhea often just hours after eating.

While Bacillus cereus isn’t exclusive to rice (it’s also found in soil, meat, gravy, and vegetables), rice is a particularly common culprit because of how it’s often handled after cooking.

The Real Risk: Letting Rice Sit Out

One big food safety myth? That rice (or any food) needs to cool completely on the counter before being refrigerated.

“There’s no need to leave it out to cool,” says Quinlan. “That’s a big myth that people have about all foods.”

Leaving rice out for hours creates the perfect warm environment for bacteria to grow.

How to Store Rice Safely

To reduce your risk of foodborne illness:

• Eat rice immediately after cooking whenever possible.

• If you plan to save leftovers, refrigerate rice within one hour especially in warm weather.

• Set your fridge to 40°F or below.

• Toss rice if it’s been sitting out at room temperature for more than 2 hours.

• Use refrigerated rice within 3–4 days, according to food safety experts.

In hot environments (90°F+), you’ve got only a one-hour window before the risk increases, says Isabel Maples, MEd, RDN, spokesperson for the Academy of Nutrition and Dietetics.

Whether it’s a backyard BBQ, potluck, or takeout situation, use a cooler with ice packs to keep rice chilled until ready to reheat.

What If You Already Ate It?

If you get sick from leftover rice, expect a short bout of food poisoning usually lasting 24–48 hours.

“Symptoms are usually self-limited,” says Sheila Rustgi, MD, gastroenterologist at Columbia University Irving Medical Center. “The body clears the toxins through vomiting or diarrhea.”

Treat symptoms at home by:

• Staying hydrated sip water or electrolyte drinks

• Avoiding solid food until nausea subsides

• Reintroducing bland foods like broth, crackers, or toast gradually

See a doctor if:

• You experience bloody vomit or diarrhea

• Symptoms last more than 48 hours

• You can’t keep fluids down or have signs of dehydration (e.g. dry mouth, dizziness, or little to no urination)

The Bottom Line

Reheating rice isn’t dangerous on its own but reheating rice that was left out too long is. To keep foodborne illness at bay:

• Cool and refrigerate rice quickly

• Toss rice that sat out for more than two hours

• Stick to the “four-day fridge rule” for leftovers

No need to fear your fried rice just handle it with care.

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