Atropine is the alkaloid of belladonna and is generally used as the sulphate.

It has no action on the unbroken skin, but is readily absorbed from mucous surfaces. It quickens the heart, contracts the blood vessels, excites the brain, dulls the irritability of the peripheral sensory nerves, increases intestinal peristalsis, dilates the pupils and dries up secretions. It causes death by paralyzing the respiratory center.

It is eliminated slowly in the urine.