Tetrahydrocannabinolic acid (THCA)

Tetrahydrocannabinolic acid, or THCA, is the non-intoxicating acidic form of THC that the living cannabis plant actually produces.

The plant makes THCA from cannabigerolic acid; heat, light, or time then remove a carboxyl group and convert it to delta-9 THC, a process called decarboxylation. Raw, unheated cannabis therefore contains mostly THCA and little active THC, which is why it is not intoxicating until heated. THCA itself binds the CB1 receptor poorly.

On a certificate of analysis, THCA and delta-9 THC are reported separately, and total THC is calculated by converting THCA to its THC equivalent, typically by multiplying by 0.877, and adding it to delta-9. Federal hemp rules use this total-THC figure, so a hemp crop can fail the 0.3% threshold on THCA alone. THCA is not CBD and does not appear in meaningful amounts in a product processed to 0.0% THC.