The herb belladonna's scientific name is atropa belladonna, and it is also commonly called deadly nightshade. It is highly toxic and shouldn't be ingested or touched by humans or pets in its plant form. Belladonna has been the basis for many medical treatments in history and modern science, and has some benefits when used appropriately. Keep in mind that even therapeutic doses of belladonna have an array of unpleasant side effects.
One of belladonna's active compounds is atropine, which is a key ingredient in the eye drops used by ophthalmologists to dilate patients' eyes for examination. This property of belladonna gives the herb its name, as Renaissance socialites in Italy often used eyedrops of a preparation of the herb to dilate their pupils, darkening their eyes and making themselves more attractive: "beautiful lady" is the meaning of "bella donna."
Belladonna is part of an herbal remedy called Bellergal--belladonna combined with ergot and phenobarbital--that has been used for menopause symptoms and pre-menstrual syndrome symptoms. However, the National Institute of Health's current recommendations on the product are that it needs further study.
Since belladonna works by paralyzing involuntary muscles, it has been used with some success as a traditional herbal remedy for irritable bowel syndrome. Studies on its use for this purpose have shown mixed results, however, and it is often used in conjunction with other treatments for maximum effect.
In turn-of-the-century medicine, belladonna was used as an antidote to overdose or poisoning from opium, heroin and other opiate drugs, since its paralytic and stimulant effects counteract those of opiates. However, modern medicine rarely uses it for this purpose, since its own effects are toxic and can easily damage health further. It also has been used as an antidote to chloroform and some herbal poisonings.
Belladonna has been used throughout history as a sleeping drink, and it effectively anesthetizes patients as well. Its uses for these purposes are almost nonexistent in modern times, as safer substances can now be given for sleep and anesthesia.
Preparations of belladonna leaves or roots have been used in various shamanic religions across the globe. As the poisons in the plant act on an adult, delirium and visions may occur, giving rise to its use by witches, seers and shamans in pagan and tribal religions. Belladonna's other effects are so unpleasant, it is not used as a recreational drug, however.
Belladonna has also been studied as a treatment for airway obstruction, ear infection, headache, autonomic nervous system disorders, radiation burn and excessive sweating, but has not been proven to have a beneficial effect on any of these conditions.