The question of how long delta-9-tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis, remains detectable after vaping is a common concern. Vaping delivers THC efficiently, leading to rapid onset of effects, but the timeline for its complete clearance is highly variable. Standard drug screenings detect not the active compound, but its inactive breakdown product, 11-nor-9-carboxy-THC (THC-COOH). Because the process of absorption, distribution, metabolism, and excretion is complex, there is no simple, universal timeline. Understanding the longevity of THC-COOH requires looking closely at how the body processes the compound and the characteristics of the individual user.
How the Body Processes Vaped THC
Inhaling THC vapor allows the compound to enter the bloodstream almost immediately through the lungs. This route of administration achieves peak plasma concentrations of THC very quickly, often within six to ten minutes of the first puff. From the bloodstream, the highly lipid-soluble THC rapidly distributes throughout the body, passing easily into organs and tissues, including the brain and fat tissue.
The liver is the main site for processing THC, where cytochrome P450 (CYP450) enzymes begin metabolism. THC is first converted into 11-hydroxy-THC (11-OH-THC), a compound that is itself psychoactive. This intermediate metabolite is then quickly broken down into the non-psychoactive form, THC-COOH, which is the primary target compound for most standard drug screenings.
Because THC is fat-soluble, it accumulates in the body’s adipose tissue, where it is slowly released back into the bloodstream over time. This slow release allows metabolites to be detected long after the psychoactive effects have worn off. The body eliminates these metabolites primarily through feces (around 65%) and urine (roughly 20%).
Individual Factors That Change Clearance Time
The process of elimination varies dramatically from person to person, meaning there is no single answer for how long THC metabolites remain detectable.
Frequency and Potency
The most significant variable is the frequency and potency of the vaping habit, as regular use causes a saturation effect. A single-use event allows the body to clear THC relatively quickly. However, chronic, heavy use leads to a buildup of THC in fat reserves that takes much longer to excrete. Vaping devices often contain highly concentrated THC oils, which contribute to this accumulation more rapidly.
Metabolic Speed
Metabolic speed is a major determinant of clearance rate, dictating how quickly liver enzymes convert THC into its inactive metabolites. People with a naturally faster metabolic rate process and eliminate THC-COOH more quickly than those with slower metabolisms. Genetic differences in the efficiency of liver enzymes can also influence this speed.
Body Composition
Body composition is a third factor, tied directly to THC’s high fat solubility. Individuals with a higher percentage of body fat have more storage sites for THC, resulting in a longer retention time for the metabolites. The slow, steady release of THC-COOH from these fat deposits means it can continue to circulate in the bloodstream and appear in urine for an extended period.
Detection Windows by Testing Method
The time frame for detection depends on the type of test administered, as each method targets different compounds or parts of the body. These windows are estimates and are subject to the individual variables discussed previously, such as use frequency and metabolism.
Urine Testing
Urine testing is the most common form of screening and primarily detects the inactive metabolite, THC-COOH. Most standard urine tests use a detection threshold of 50 nanograms per milliliter (ng/mL). For a person who vapes THC only once, the metabolites are typically detectable for approximately three to seven days. Moderate use, defined as several times per week, can push the detection window out to between seven and 15 days. In cases of chronic, daily, or heavy use, the saturation of fat tissue can lead to detection times exceeding 30 days, and in rare, extreme cases, up to 90 days after the last use.
Blood Testing
Blood testing measures the concentration of active THC in the bloodstream, making it a reliable indicator of very recent use or current impairment. Because the body quickly clears active THC from the blood, the detection window is short. For occasional users, blood tests typically detect THC for 12 to 48 hours. In heavy, chronic users, where fat stores constantly release THC back into the blood, the detection time may be extended up to seven days.
Saliva Testing
Saliva or oral fluid tests focus on detecting recent use by measuring active THC present in the oral cavity. This non-invasive method is often used to screen for impairment in workplace or roadside settings. The typical detection window for a saliva test is generally between 24 and 72 hours following the last use.
Hair Follicle Testing
Hair follicle testing offers the longest detection window. It captures metabolites incorporated into the hair shaft through the bloodstream, providing a historical record of consumption rather than recent use. Hair tests typically sample a 1.5-inch segment of hair, which corresponds to a standard 90-day window of use, based on the average rate of human hair growth.