Cocaine
The Devil’s dandruff, Peruvian marching powder, nose candy, whatever you want to call it, cocaine was actually included in many types of medicines and drugs (not only in the soft drink called Coca-Cola). Due to its energizing effects, people believed that cocaine should be part of a healthy lifestyle. So, in the latter part of the 19th century and early 20th century, cocaine was actually promoted as a miracle drug.
It was even praised by some popular figures in medical history (surgeon William Halsted and even Sigmund Freud). According to history buffs, Freud even mentioned this “wonder drug” in a letter he wrote for his wife, saying that he takes a dose regularly against indigestion and depression.
Well, today’s medicine would strongly disagree with Freud’s beliefs since this powerful drug can damage your heart and brain irreversibly.