// Definition
A dose-dependent phenomenon where a substance produces opposite effects at low versus high doses. In cannabis, low doses of THC can effectively control nausea, while very high doses may paradoxically promote nausea, potentially explaining cannabis hyperemesis syndrome.
// From the Episode
Dr. Mark Scialdone explained the biphasic concept in the context of discussing cannabis hyperemesis syndrome (CHS), noting that Raphael Mechoulam demonstrated sublingual THC below psychoactive levels could completely block chemotherapy-induced nausea in children. At extremely high doses, however, a biphasic inversion may trigger the opposite response. He stated the neem oil theory of CHS has been 'completely debunked' and that the true mechanism likely involves dose-dependent receptor sensitivity.