Mescaline is a naturally-occurring alkaloid which causes hallucinogenic effects similar to those of LSD and psilocybin. It has been used for religious rituals by North American Natives as far back as 5700 years ago and has been claimed to be a viable treatment for depression, anxiety, headache, obsessive compulsive disorder and addiction to certain substances, such as ethanol.
Consumption of substance outside of the Native American Church however is illegal which greatly limits further studies. In fact very few research has been done since the 1970s. A recent literature review however concluded that 3,4,5-trimethoxyphenethylamine, the alkaloid found in the San Pedro cactus produces mild intoxications and is unlikely to produce life-threatening symptoms. This combined with the absence of any signs of addiction or dependence strengthens the case for the use of mescaline as a potential therapeutic drug.
Read the article from the National Library of Medicine here.