Cyanide poisoning is not a nice way to go. Essentially it’s open-air suffocation. Cyanide ions in the body interact with an enzyme called cytochrome oxidase. This enzyme works with hemoglobin in the blood. It preferentially picks up cyanide when it should be picking up oxygen, meaning the body slowly dies for lack of “air.”
There’s a classic joke about how to get intoxicated at hospitals by claiming you drank methanol to get an IV with an ethanol solution. It’s not that methanol will kill you or make you blind… The problem is that the liver enzyme alcohol dehydrogenase turn methanol into formaldehyde (or methyl aldehyde). Ethanol binds to the same enzyme to inhibit the production of formaldehyde.