Cannabis has been used for thousands of years for medicinal, spiritual, and recreational purposes. The psychoactive effects of cannabis were likely discovered and exploited by ancient people in different parts of the world, including China, India, and the Middle East.

In 1964, Israeli scientist Raphael Mechoulam and his colleagues were the first to isolate and synthesize THC. This allowed for the pharmacological properties of THC to be studied in detail.

In the 1970s, the U.S. government classified cannabis as a Schedule I drug, which means it was considered to have a high potential for abuse and no accepted medical use. This classification severely restricted research into the potential medical benefits of THC and other cannabinoids found in cannabis. However, in the 1980s, researchers began to study the potential therapeutic uses of THC and other cannabinoids. They discovered that THC can alleviate pain, nausea, and inflammation, and has potential as a treatment for certain mental health conditions.

In the 1990s, medical marijuana was legalized in California, and several other states followed suit in the following years. This allowed patients with certain medical conditions to access cannabis and its active compounds, including THC, legally.

In recent years, the legalization of cannabis for both medical and recreational purposes has spread to many parts of the world, including Canada, Uruguay, and several U.S. states. This has led to increased research into the potential medical benefits of THC and other cannabinoids, as well as the development of new cannabis-based products for consumers. Today, THC is still classified as a Schedule I drug by the U.S. government, but many researchers and medical professionals believe that it has significant medical potential and should be reclassified.