THCa, or tetrahydrocannabinolic acid, is a non-psychoactive cannabinoid found in raw cannabis. It’s the precursor to THC (tetrahydrocannabinol), which is the compound responsible for the “high” associated with cannabis use. THCa converts into THC when it’s heated — a process known as decarboxylation. That means THCa won’t get you high unless it's heated through smoking, vaping, or cooking.