12. Deadly Nightshade Eye Drops
The scientific name of Deadly Nightshade, Atropa belladonna, is proof of its widespread use as a beauty product. Belladonna, in Italian, means beautiful woman and became attached to the plant due to the trend of Italian renaissance women using eye drops concocted from nightshade to dilate their pupils, as wide doe-like eyes were a prized beauty ideal of the era.
Belladonna is one of the most toxic plants in the eastern hemisphere. Ingesting the plant, especially the root, can cause heart disease, mental illness, spontaneous abortion and more. Children are especially at risk from Belladonna poisoning due to the attractive appearance of the dark-purple berries and the fact that, unlike most poisonous berries, they actually do taste quite sweet and pleasant.
The roots have the highest concentration of the toxic alkaloids that make the plant deadly, but every part of the plant is poisonous to varying degrees. Prolonged use of the eye drops would have caused visual disturbances, inability to focus the eyes, increased heart rate, and eventually blindness with enough use. This product is one cosmetic you may well have used yourself at one point though, as a safer more refined version is still used today to dilate pupils during eye exams.