Belladonna has a long history of medicinal applications in healthcare. Belladonna alkaloids are anticholinergic, which means that it works by blocking the certain nerve impulses involved in the parasympathetic nervous system, which regulates certain involuntary bodily functions or reflexes, including pupil dilation, heart rate, secretion of glands and organs, and the constriction of the bronchioles in the lungs and the alimentary canal (digestive tract). Belladonna relaxes the smooth muscles of the internal organs and inhibits or dries up secretions (e.g., perspiration, mucous, breast milk, and saliva).
Belladonna alkaloids, the active ingredients of the plant, include atropine and scopolamine. These alkaloids are extracted from the leaves and root of the plant and administered either alone or in combination with other herbal remedies or prescription medications. However even tiny doses are toxic and should only be taken by prescription.