Is Leftover Rice Safe? Why Rice Left Out Can Make You Sick

The risk with leftover rice comes from rice that sits out at room temperature. The reason is a bacterium called Bacillus cereus. According to the CDC, it is frequently present in uncooked rice, and its heat-resistant spores may survive cooking. If cooked rice is then held at room temperature, the bacteria multiply and make a heat-stable toxin that can survive brief heating, such as stir-frying. That is why reheating the rice later does not fix a rice that was left out too long.

1. What happened in the CDC's fried rice outbreak

The CDC's Morbidity and Mortality Weekly Report describes a real case from July 1993 in Virginia. A catered lunch was served to 82 children and nine staff at two day care centers. Of 67 people who ate the lunch, 14 (21%) became ill, and none of the 13 who did not eat it did. Illness occurred in 14 of 48 people (29%) who ate the chicken fried rice, and in none of the 16 who did not.

The timeline is the useful part:

1. The rice was cooked the night of July 20 and cooled at room temperature before it went into a refrigerator.
2. On the morning of the lunch, it was pan-fried in oil with cooked chicken.
3. It was delivered at about 10:30 a.m., held without refrigeration, and served at noon without reheating.

Symptoms were mostly nausea (71%), abdominal cramps (36%), and diarrhea (14%). The median time from eating to symptoms was 2 hours, with a range of 1.5 to 3.5 hours. Symptoms resolved a median of 4 hours after they began. B. cereus was found in the leftover rice at more than a million organisms per gram.

Health officials recommended that cooling rice or any food at room temperature stop, that food be kept below 41°F or above 140°F, and that a thermometer be used to check food temperatures.

2. Why this bacterium is different

B. cereus is a spore-forming bacterium, and the CDC says its heat-resistant spores may survive cooking. The CDC report describes two forms of illness:

• Emetic (vomiting) syndrome, with an incubation period of 1 to 6 hours, caused by a highly stable toxin that survives high temperatures and exposure to stomach enzymes and acid. This is the one linked to fried rice and was the type in the outbreak.
• Diarrheal syndrome, with an incubation of 6 to 24 hours, caused by a heat- and acid-sensitive enterotoxin.

Fever is uncommon with either one, and the CDC says the illness is usually self-limiting and not severe. It also says outbreaks are likely underreported. The key point for cooks is the stable toxin: the CDC says it can survive brief heating, such as stir frying.

3. What USDA says to do with leftovers

FSIS gives the general rules for any cooked food, and rice should follow them:

• Two hours. Refrigerate leftovers within 2 hours of cooking or of removing food from a warming appliance. Throw away perishable food left at room temperature for more than 2 hours, or 1 hour if the temperature is over 90°F.
• Hot food stays hot. Food held hot should stay at 140°F or warmer. Bacteria grow rapidly between 40°F and 140°F.
• Cool it fast. Divide large amounts into shallow containers so food reaches 40°F or below quickly. FSIS says hot food can go directly into the refrigerator or be chilled first in an ice or cold water bath.
• Cover it. Wrap leftovers in airtight packaging or containers.
• Time limit. Leftovers keep in the refrigerator for 3 to 4 days, or in the freezer for 3 to 4 months for best quality.
• Reheat to 165°F. Measure with a food thermometer, and cover the food to hold in moisture and heat it evenly.

4. Applying it to rice

The CDC incident points to the habits that matter:

1. Do not cool a pot of rice on the counter overnight. The Virginia rice cooled at room temperature before refrigeration. Spread rice into shallow containers right after the meal.
2. Count the 2 hours from when the rice finished cooking, including time on the table. FSIS counts the 2 hours from cooking or from removing food from an appliance that keeps it warm.
3. If you keep rice warm, keep it at 140°F or above. FSIS gives 140°F as the line for hot food.
4. Do not buy time with reheating. FSIS says to reheat leftovers to 165°F, but the CDC says the toxin can survive brief heating. If rice sat out too long, throw it out.
5. Be careful with cooked rice used for fried rice later. The CDC notes that fried rice is a leading cause of this type of food poisoning in the United States. Cook rice for fried rice, chill it promptly in shallow containers, and fry it within the refrigerator window.

5. Does it apply to other foods?

The CDC report is about rice, so this page does not extend its findings to other foods. FSIS's leftover rules apply to cooked food in general.

6. Key takeaways

• B. cereus spores in uncooked rice can survive cooking, per the CDC.
• If cooked rice sits at room temperature, the bacteria grow and make a toxin that survives brief heating, including stir-frying.
• Refrigerate rice within 2 hours (1 hour above 90°F), in shallow containers, and eat it within 3 to 4 days.
• Reheat to 165°F, but do not rely on reheating to rescue rice that was left out.
• In the Virginia outbreak, rice cooked the night before and cooled at room temperature caused illness in 14 people within a median of 2 hours.