poisonous

A poisonous substance or situation is one that can cause harm or even death if not handled carefully.

The word "poisonous" often comes up when talking about things that might seem harmless at first but can actually be very bad for you. For example, a snake's venom is poisonous to humans, so we try to avoid getting bitten by it. Some plants and berries are also poisonous if eaten, which is why parents warn their kids not to touch certain wildflowers or try new fruits they find in the woods. Even some chemicals used in our daily lives can be poisonous if we're not careful with how much of them we use.