Most drugs need to be kept within a certain temperature range, otherwise they might undergo a chemical reaction into something else entirely. To my knowledge, I can’t think of any that would kill you if this happened, but they wouldn’t be as effective.
However, there is something that many people don’t think about when they take medicine, and that is how your medicines might be affected by the food you eat. For instance, grapefruits might seem like the perfect thing to have for breakfast, right? Fresh fruit, rich in Vitamin C and fiber. However, grapefruit is known to contain something that can stop your body from breaking down certain drugs. This means that even if you take the right number of pills as prescribed by your doctor, you could accidentally overdose if you’d eaten a grapefruit on the same day.
So, you need to be careful to read the fine print on the bottle!