Strychnine is the alkaloid of nux vomica, and is generally used as the sulphate or nitrate.

It has no action on the skin or mucous membranes, but is readily absorbed from the latter.

It is a stimulant to the heart, contracts the blood vessels, stimulates the brain and spinal cord, and especially the respiratory and vasomotor centers. In poisonous doses it causes convulsions by over-stimulating the spinal cord. It causes death by tetanus.

It is excreted in the urine.