Again, how you store it before heating can lead to problems. The Food Standards Agency stated that “Uncooked rice can contain spores of bacteria that can cause food poisoning. When the rice is cooked, the spores can survive…however. Then, if the rice is left standing at room temperature, the spores will multiply and may produce poisons that cause vomiting or diarrhea. Reheating the rice won’t get rid of these poisons.”