Tox In Focus

Focused Clinical Reference

Vol. 20 · THC / Cannabis · July 2026

Drug Quick Reference

Drug Class / Mechanism

Cannabinoid (CB-1/CB-2 partial agonist)

Delta-9-THC; urine metabolite cTHC

Street Names

Weed, pot; concentrates: dabs, wax, shatter

Dronabinol (Rx synthetic THC)

Routes of Administration

Smoked, vaped

Edibles, concentrates, topicals

Commonly Detected With

CBD products (not measured) · Delta-8-THC (isomer)

Metabolism

THC to inactive cTHC; ~15 to 20% renal

Highly lipophilic; accumulates in fat

Window of Detection

Urine cTHC: days (single) to ~40 days (chronic)

Oral fluid THC: ~2 to 24 h single, up to 48 h chronic

Control Status

Federal: Schedule I (recreational, bulk, synthetic)

Schedule III: FDA-approved and state-licensed medical (2026)

THC

cTHC, chronic-use windows, delta-8, and reading new use vs. residual

Cannabis testing measures the inactive metabolite carboxy-THC (cTHC) in urine and THC in oral fluid. Because THC is highly lipophilic and accumulates in fat, the urinary window ranges from a few days in occasional users to up to 40 days in chronic users, which makes distinguishing new use from residual excretion the central interpretive challenge.¹

Why This Matters Now

Federal cannabis policy is shifting: as of April 2026 the Justice Department placed FDA-approved marijuana products and state-licensed medical marijuana into Schedule III, while recreational, bulk, and synthetically derived THC remain Schedule I, and a DEA hearing on broader rescheduling is underway in mid-2026.² Rescheduling does not change how a cTHC result is interpreted, but it changes the legal and program context around a positive.

⚠ A single cTHC value cannot distinguish new use from residual excretion in a chronic user. Use serial, creatinine-normalized results to judge abstinence versus reuse.³

Clinical Presentation

INTOXICATION

Euphoria, relaxation

Impaired short-term memory, coordination

Tachycardia

Anxiety, paranoia (higher doses)

Concentrates/edibles: stronger, delayed effects

WITHDRAWAL

Irritability, anxiety

Insomnia, vivid dreams

Decreased appetite

Restlessness

Onset within ~1 day; days to weeks

Important: A rising or persistent cTHC does not by itself prove new use in a chronic user; residual excretion from fat can last weeks. Creatinine normalization and serial values are essential before concluding reuse.

UDT Considerations

Urine testing detects cTHC; oral fluid detects THC and reflects more recent use. The assay does not measure CBD, and oral fluid cannot separate delta-8 from delta-9-THC, so a legal delta-8 product can produce a positive.⁴ For chronic users, review measured and creatinine-normalized cTHC over time to distinguish new use from residual excretion.³

Clinical Guidance

Interpret cTHC with the use pattern in mind; chronic users can stay positive up to ~40 days.¹
Use serial, creatinine-normalized results to separate new use from residual excretion.³
Recognize that delta-8-THC and other isomers can cause positives and are not distinguished in oral fluid.⁴
Do not attribute a positive to passive exposure except under extreme conditions.⁵
Note that CBD is not measured and dronabinol use may not be detectable in oral fluid.

Point-of-Care Testing Availability

Available strips

Cannabinoid immunoassays screen for cTHC; confirm positives by LC-MS/MS.

Clinical use

Passive smoke exposure rarely causes a positive except under extreme conditions.

Limitations

Oral fluid cannot distinguish delta-8 from delta-9-THC.

THC | Clinical & Program Guidance

Tox In Focus Vol. 20 · July 2026 · Page 2 of 2

Interpreting the Test Result

▲ If Testing Is Positive

Confirms THC exposure. cTHC in urine, or THC in oral fluid, indicates cannabis or THC-product use.

New use vs residual is the question. In chronic users a positive may be residual; use the window grid and serial results.³

Source may be a legal isomer. Delta-8-THC can produce a positive and is not distinguished in oral fluid.⁴

▼ If Testing Is Negative or Not Done

Timing and cutoff. Occasional use clears in days; a negative may reflect timing or low dose.

Oral fluid is shorter. A negative oral fluid does not exclude earlier use captured by urine.

CBD not measured. A negative says nothing about CBD product use.

Detection Windows by Matrix

Matrix	Analyte	Single use	Chronic use
Urine	cTHC	A few days	Up to ~40 days
Oral fluid	THC	~2 to 24 h	Up to ~48 h

Wide urinary variability reflects THC storage in fat; use creatinine-normalized serial results to interpret chronic users.

Key References

Huestis MA, Mitchell JM, Cone EJ. Urinary excretion profiles of 11-nor-9-carboxy-THC after single smoked doses of marijuana. J Anal Toxicol. 1996;20(6):441-452.
US Drug Enforcement Administration. Marijuana Rescheduling Regulatory Actions. 2026.
Huestis MA, Cone EJ. Differentiating new marijuana use from residual drug excretion in occasional marijuana users. J Anal Toxicol. 1998;22(6):445-454.
National Laboratory Certification Program. Effects of delta-8-THCA on initial and confirmatory testing for cannabinoids in urine. 2020.
Cone EJ, et al. Non-smoker exposure to secondhand cannabis smoke I: urine screening and confirmation results. J Anal Toxicol. 2015;39(1):1-12.

DISCLAIMER: This document is intended for clinical reference and educational purposes only. It does not constitute medical, legal, or professional advice and should not replace independent clinical or programmatic judgment. Content reflects published data available at time of preparation. ToxiPharm LLC makes no warranties regarding completeness or applicability in all settings. | © 2026 ToxiPharm LLC | toxipharm.org