Arsenic is used in the form of the trioxide.

It has no action on the unbroken skin except there is long exposure. It is intensely irritant and corrosive to mucous membranes, hence it is one of the corrosive poisons, causing violent vomiting, purging and ulceration. It is slowly absorbed and slowly excreted, readily depositing in the organs of the body. It causes death in acute poisoning by acting reflexly through the pneumogastric nerves to paralyze the heart.

It is eliminated principally in the urine, and may cause nephritis by irritating the kidneys.