The durham-humphrey amendment was issued in 1951 and divided medications in two categories: legend drugs, which are those medications that can only be sold to a person who brings a prescripction signed by a health practitioner, and over-the-counter OTC medications that can be sold freely to any customer in a drug store.
Therefore, dangerous self-medication practices, such as consuming drugs which are unsafe if such consumptions are not supervised by a doctor, have been removed as a result of the introduction of this legislation.