Neurotoxins are substances that can harm or disrupt the normal functioning of the nervous system. They can be produced by various organisms, including certain types of bacteria, plants, and animals. When neurotoxins enter the body, they can interfere with the communication between nerve cells, leading to symptoms such as paralysis, confusion, or even death, depending on the severity of exposure. Common examples of neurotoxins include botulinum toxin, produced by the bacterium Clostridium botulinum, and tetrodotoxin, found in some species of pufferfish. These toxins can be dangerous, but they are also studied for potential medical uses, such as in cosmetic treatments and pain management.