Compounds responsible for the aroma of cannabis and many other plants may offer a surprising new way to relieve chronic pain. Researchers found that several cannabis-derived terpenes significantly reduced pain in mouse models of fibromyalgia and post-surgical pain, with one terpene, geraniol, showing especially strong effects. Unlike THC, these compounds are not associated with psychoactive effects, making them a potentially attractive alternative for pain treatment.
They started as medicines and were concentrated, distilled, and extracted to the point where the medicine it became was deadlier than the cure it provided.
Coca leaves are still consumed medicinally/recreationally in some parts of south america.
Poppy seeds have a whole history of being abused and weaponized through the silk road.
Marijuana has faced a similar story, though without the deaths. This hasn’t stopped governments around the world from conflating the deaths caused by other things with the use of medicines that in no way cause death.
I have to point out that in medicine we use the derivatives from cocaine, novacaine, lidocaine, benzocaine etc as potent short/medium term anaesthetics. Drugs like these make dental extractions for example relatively painless today. Pure cocaine was used previously but was far more toxic to the liver and had a much higher incidence of allergic reaction than its modern derivatives.