Belladonna (Atropa belladonna) is a poisonous plant that has been used as a medicine since ancient times. It is named “Belladonna” for the “beautiful women” of Renaissance Italy, who took it to enlarge their pupils, which they found more alluring.

But it also goes by a more sinister name — deadly nightshade — that implies a darker history. Indeed, not only are its dark berries sometimes known as murderer’s berries, sorcerer’s berries, and even devil’s berries, they are thought to be the poison that caused Juliet to appear dead in Shakespeare’s “Romeo and Juliet.”

Despite its ominous name, it’s highly unlikely that you’ve never used belladonna. It’s an ingredient in a number of medications, and also sold as a supplement. When your eye doctor dilates your eyes, belladonna is in the eye drops.

But how safe is it?

Belladonna, native to Europe and parts of Asia, can grow up to 5 feet. It has purple flowers and dark, inky berries that are slightly sweet.

Belladonna’s so toxic that eating a small quantity of its leaves or berries can be fatal to humans, particularly children, and some animals. Simply touching the leaves can irritate your skin. According to the National Institutes of Health (NIH), it is not safe when taken orally.

Despite its toxicity, belladonna has some medicinal benefit. The chemicals atropine and scopolamine, which are derived from belladonna, have important medicinal properties.

Atropine and scopolamine have almost the same uses, but atropine is more effective at relaxing muscle spasms and regulating heart rate. It’s also used to dilate the pupils during an eye exam. Atropine can also be an antidote for insecticides and chemical warfare agents.

Scopolamine has many sources, including belladonna, and is more effective at reducing body secretions, such as stomach acid. It can also help motion sickness, via skin patch.

Combined with Phenobarbital or other medications, these chemical derivatives of belladonna (atropine or scopolamine) are used to treat a number of conditions, including:

  • irritable bowel syndrome
  • spastic colon
  • stomach ulcers
  • Parkinson’s disease
  • diverticulitis
  • motion sickness
  • excessive nighttime urination
  • pink eye

You can purchase belladonna products over the counter at your local pharmacy or health food store. One large American manufacturer of homeopathic products even sells teething tablets and gels that contain belladonna. (Although the U.S. Food and Drug Administration issued a safety recall for the tablets, they are back on the market.)

Usually marketed as nutritional supplements, belladonna is sold in tablets, tincture (liquid), ointments, and in a pump spray. Companies claim it helps with:

  • colds
  • flu
  • fever
  • cough
  • sore throat
  • inflammation
  • joint and back pain
  • earache
  • gout

Belladonna should be safe for you if your doctor prescribes it and you take it as directed. If you are considering using an over-the-counter product, remember that there are a number of concerns about belladonna specifically, and herbal products in general.

The U.S. Food and Drug Administration (FDA) doesn’t test homeopathic and herbal supplements for safety or effectiveness. According to the NIH, there isn’t enough evidence to prove that belladonna is effective for the uses we see on product labels.

When it comes to deadly nightshade, unless it’s been prescribed by your doctor, you might want to take a pass.