The list I have compiled here is not just a list of the top 10 most toxic substances known to man. That would be too easy and not really relevant to anyone. This list is all those deadly poisons that have, over the years, been used by humans to kill each other; either individually or en masse. Arsenic is one of the classics.
The risk of addiction is nearly non-existent with Robaxin as it is not a direct pain reliever, but instead alleviates muscle spasm, which can lead to tension-driven pain. Robaxin is commonly used as a replacement for other muscle relaxers that do have the potential to be habit forming.
Methocarbamol is a muscle relaxant and active ingredient of Robaxin. It is FDA-approved for the treatment of muscle spasms and skeletal muscle conditions. How the drug works to prevent muscle spasms is not yet known, but it is similar in structure to guaifenesin (another muscle relaxant) and appears to be quite safe when used correctly.