For those drugs where this is both common and dangerous, (but not due to drug abuse), drug companies and pharmacies are likely to self regulate sales of these drugs to preserve their good name.
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No pharmacist wants to get a reputation for killing their clients
Companies that sell tobacco knew that tobacco is dangerous, and did not self-regulate sale of tobacco enough to stop people from dying from it.
On the other hand it’s not like homeopathy is unheard of today...
Homeopathy exists today because the FDA has a specific exception for homeopathy baked in, because Senator Copeland, who helped create the Food, Drug, and Cosmetics act in 1938 which gave authority to the FDA, was a homeopath and wrote the exception into the FDCA. The FDA is barely starting to remove the exception in modern times.
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Companies that sell tobacco knew that tobacco is dangerous, and did not self-regulate sale of tobacco enough to stop people from dying from it.
Homeopathy exists today because the FDA has a specific exception for homeopathy baked in, because Senator Copeland, who helped create the Food, Drug, and Cosmetics act in 1938 which gave authority to the FDA, was a homeopath and wrote the exception into the FDCA. The FDA is barely starting to remove the exception in modern times.