How long does urine test positive for Tetrahydrocannabinol (THC)?

From the Guidelines

THC can be detected in urine for 1–3 days after use, and up to 30 days or more in heavy users. The detection time of THC in urine varies depending on several factors, including the frequency and amount of cannabis use, individual metabolism, body fat percentage, hydration levels, and the sensitivity of the test being used 1. For example, the metabolite 11-Nor-9-carboxy-THC, which is used as a biomarker for cannabis use, can be detected in urine for 1–3 days after use, and up to 30 days or more in heavy users 1.

Factors Affecting Detection Time

• Frequency and amount of cannabis use: Heavy users may test positive for longer periods than occasional users 1
• Individual metabolism: People with faster metabolisms may eliminate THC more quickly than those with slower metabolisms 1
• Body fat percentage: THC is fat-soluble and stored in fat cells, so people with higher body fat percentages may test positive for longer periods 1
• Hydration levels: Drinking plenty of water may help to flush out THC metabolites more quickly, but this can also depend on the sensitivity of the test being used 1
• Sensitivity of the test: More sensitive tests can detect lower concentrations of THC metabolites, resulting in longer detection windows 1

Important Considerations

• A negative test result does not necessarily mean that an individual is not using cannabis, as the test may not be sensitive enough to detect low levels of THC metabolites 1
• Providers should be aware that adolescents may not always disclose cannabis use, and repeated screening and building trust may be necessary to detect use 1

From the Research

Urine Positive THC Detection Times

• The detection time for THC in urine can vary depending on several factors, including the dose and method of administration, as well as individual factors such as metabolism and hydration level 2.
• A study published in 2003 found that after controlled oral administration of delta9-tetrahydrocannabinol to humans, the mean detection rate for THC in urine was less than 0.2% at low doses, but increased to 23-46% at higher doses, with detection times ranging from 5 to 118 hours 2.
• Another study published in 2020 found that after inhalation of vaporized CBD-dominant cannabis, four urine samples screened positive for THC at a cutoff concentration of 15 ng/mL, with detection times ranging from 1 to 5 days 3.
• A 2022 study found that after acute administration of vaporized CBD-dominant cannabis, three participants provided a total of six urine samples with THC concentrations greater than or equal to 15 ng/mL, with detection times ranging from 1 to 58 hours 4.

Factors Affecting Detection Times

• The method of administration can affect the detection time for THC in urine, with oral administration resulting in higher peak concentrations and longer detection times compared to vaporized administration 3, 4.
• The dose of THC can also affect the detection time, with higher doses resulting in longer detection times 2.
• Individual factors, such as metabolism and hydration level, can also affect the detection time for THC in urine 2.

Differentiating Marijuana Use from CBD Use

• A 2021 study developed an assay to differentiate marijuana use from the use of CBD products contaminated with THC, using the ratio of CBD to THC metabolites in urine 5.
• The study found that CBD users had higher concentrations of CBD metabolites in their urine compared to THC metabolites, while marijuana users had higher concentrations of THC metabolites 5.
• The assay was able to accurately distinguish between marijuana use and CBD use in 85% of cases, with a sensitivity of 92% and a specificity of 88% 5.