If cooked rice is left at room temperature—on the stove, in the rice cooker, or on the counter—for more than an hour, those spores can wake up and multiply rapidly. As they grow, they release toxins that are heat-resistant, meaning reheating the rice later may not make it safe again.
This is what makes fried rice syndrome particularly dangerous: even rice that looks, smells, and tastes normal can still cause illness.
Fast-Onset Food Poisoning Symptoms
Food poisoning caused by contaminated rice often appears much faster than people expect. Symptoms can begin within 1–6 hours after eating and may include:
Nausea and vomiting
Stomach cramps
Fever
Watery or severe diarrhea
Headache and weakness
In more serious cases, dehydration and electrolyte imbalance can develop, especially in children, older adults, pregnant women, and people with weakened immune systems.
