Why is cyanide considered an extremely dangerous poison?

Cyanide is considered an extremely dangerous poison primarily because it interferes with the body's ability to use oxygen at the cellular level. It binds to cytochrome c oxidase, an essential enzyme in the mitochondrial respiratory chain, effectively halting aerobic metabolism. This means that, even if the body has sufficient oxygen in the bloodstream, the cells cannot utilize it to produce energy, leading to cellular hypoxia and potentially fatal consequences.

This mechanism explains why individuals exposed to cyanide can rapidly fall into a critical state, despite normal or even elevated levels of blood oxygen. Unlike other respiratory issues such as bronchoconstriction or damage to lung tissue, which take time to affect oxygen availability, cyanide's action is swift and lethal, causing biological systems to fail almost immediately at a cellular level.