Mescaline and psilocybin mushrooms are hallucinogenic substances that have been used for thousands of years. Mescaline is derived from cacti and psilocybin is found in certain mushroom species. Both substances cause visual hallucinations and altered sensory experiences that can last from 3 to 12 hours depending on dosage. Studies have shown that psilocybin in particular may help treat conditions like anxiety and depression with no risk of addiction when used responsibly.