Carboxy THC, also known as delta-9-carboxy-tetrahydrocannabinol (THC-COOH), is a non-psychoactive metabolite of tetrahydrocannabinol (THC), the primary psychoactive component of cannabis/marijuana. When THC is consumed, it is metabolized by the body into inactive compounds, including carboxy THC, which can remain detectable in urine for several days following occasional use and longer with more frequent use. Carboxy THC has no psychoactive effect and is not responsible for impairment, unlike delta-9-THC, which is the compound responsible for impairment. The presence of carboxy THC in urine is a strong indicator that the patient has used cannabis/marijuana. Carboxy THC can be detected through toxicological testing in blood and urine samples.