THCa

THCA, or tetrahydrocannabinolic acid, is a non-psychoactive cannabinoid found in cannabis plants as the carboxylated precursor to delta-9-tetrahydrocannabinol (THC). In chemical terms, THCA is the acidic form of THC, bearing a carboxyl group that is lost as carbon dioxide when heated, a process known as decarboxylation. This reaction converts THCA to THC, the compound primarily responsible for the psychoactive effects of cannabis.

In cannabis, THCA is synthesized from cannabigerolic acid (CBGA) by the enzyme THCA synthase; CBDA synthase converts CBGA to cannabidiolic acid (CBDA). THCA is usually the most abundant cannabinoid in fresh plant material, but it is typically present as THCA rather than THC until decarboxylation occurs during drying, smoking, vaping, or cooking.

THCA is not considered psychoactive in its native acid form, as it has limited affinity for the CB1 receptor in the brain. Some research has explored potential therapeutic properties, such as antiemetic, anti-inflammatory, and neuroprotective effects, but robust clinical evidence is lacking. THCA is often measured separately from THC in plant material and products to assess potency and legal compliance.

Legal status varies by jurisdiction. In many regions, regulation distinguishes THCA-containing products from pre- or post-decarboxylation THC, and some rules apply to total delta-9-THC equivalence rather than THCA content alone. Storage, processing, and heating can influence THCA levels in finished products.