Overdose happens when someone uses too much of a drug or medicine. This can be very dangerous and can make the person very sick or even die. Just like when you eat too many sweets or candies, having too much medicine or drugs in your body can make you feel really sick. Some drugs are okay if you take just the right amount, but if you take too much, it can hurt your body. So always make sure to listen to adults and follow instructions carefully when taking medicine. And if you ever see someone who looks really sick or like they're having trouble breathing, it's important to tell an adult right away.