Be careful with your leftover rice.
While it's one of the most common foods (in some countries providing up to three-quarters of daily energy intake), rice may not be the best choice to eat as leftovers. Why? Rice of all types can be contaminated with the spore-forming bacteria called Bacillus cereus. Present but dormant in all raw brown and white rice varieties, the spores are not killed by the boiling cooking water—instead, they are actually revived and converted into potentially harmful live bacteria as the rice cools. If the rice is consumed shortly after cooking there is no problem, as very few bacteria have had the time to multiply. But if the rice is saved, and even stored in the refrigerator for too long, the amount of bacteria will grow. With enough time, the bacteria, which is responsible for 2 to 5 percent of all reported food-borne illnesses, can form enough heat-stable toxin to make a consumer sick within a few hours. The risk is not high, but has most commonly been observed in cooked rice that has been left out for several hours, then refrigerated, and then fried.
To play it safe, follow these guidelines from the USDA when storing and reheating leftover rice: