How Long Does THC Stay in Your System? Testing Windows and Factors

Whether you’re facing a workplace screening, planning a trip abroad, or simply curious, understanding how long tetrahydrocannabinol (THC) and its metabolites linger in your body is key. Detection times vary wildly based on test type, personal physiology, and even the kind of product you use. In this guide, we’ll walk through metabolism, testing windows, influencing factors, and practical tips to help you stay one step ahead.

How Your Body Processes THC

• Absorption: Smoking or vaping sends THC into the bloodstream almost instantly, while edibles peak between 30 minutes and two hours.
  
  

• Distribution: THC travels through the blood to the brain and fatty tissues, where it binds CB1 receptors to produce psychoactive effects.
  
  

• Metabolism: In the liver, THC becomes 11-hydroxy-THC (active) and then THC-COOH (inactive). Drug tests target THC-COOH because it lingers longest.
  
  

• Elimination: THC-COOH exits via urine and feces; small amounts embed in hair and appear in saliva.

Urine Testing Window

Urine assays look for the inactive metabolite THC-COOH, which accumulates in the body fat before being filtered out by the kidneys. Occasional users—those who consume cannabis once or twice a week—will typically test positive for three to seven days after their last session. If you’re a regular user (several times per week), expect metabolites to linger between one and three weeks. Daily or heavy consumers can remain above the standard screening cutoff (50 ng/mL initial, 15 ng/mL confirmatory) for a month or more. 

Because THC-COOH binds to fat cells, individuals with higher body fat percentages often clear it more slowly. Drinking extra water can dilute your sample. Still, extreme dilution can also trigger a retest.

Saliva Testing Window

Oral-fluid screens detect unmetabolized THC itself, making them useful for pinpointing very recent use. After smoking or vaping, THC shows up in saliva almost immediately and usually disappears within one to three days for casual users. Heavy users may still register up to a week later. Keep in mind that eating, drinking, or brushing your teeth shortly before a test can sometimes lower detectable levels, so give yourself at least 15–30 minutes between oral hygiene and the sample.

Blood Testing Window

Because blood tests measure the parent THC compound rather than its metabolites, they’re the go-to for determining current impairment. THC peaks in plasma about five to 15 minutes post-inhalation and falls below typical detection thresholds in two to six hours. 

Metabolites like THC-COOH can stick around in the bloodstream for up to 24–48 hours, but most standard blood panels focus solely on active THC. Given the invasive collection process and narrow window for detecting THC, blood screens are rare outside of accident investigations or forensic contexts.

Hair Testing Window

Hair analysis offers the longest lookback period—up to 90 days—by capturing tiny amounts of THC-COOH as hair grows. It won’t flag use in the five to ten days before sampling (while the new growth emerges), but once that window closes, you get a nearly three-month usage profile. 

Because hair testing isn’t affected by hydration or recent diet, it’s prized for high-security or legal screenings. Labs mitigate external contamination by washing and segmenting samples, ensuring the results reflect actual intake rather than environmental exposure.

Key Factors That Influence THC Clearance

Everyone’s body handles THC differently. While time is the most reliable “detox” factor, several personal and lifestyle variables can speed up or slow down clearance:

• Use Frequency & Dosage: Occasional users (1–2 sessions per week) often test negative within 3–7 days, while daily consumers may carry detectable THC-COOH for 30 days or more. Lowering both how much and how often you use is the single biggest way to shorten detection times.
  
  

• Body Composition: THC is fat-soluble, so it accumulates in adipose tissue. Individuals with higher body-fat percentages release metabolites more slowly. Conversely, leaner people tend to clear THC-COOH faster, all else being equal.
  
  

• Metabolic Rate: A faster metabolism processes and eliminates THC metabolites more quickly. Factors such as genetics, thyroid function, and overall health influence metabolic speed, so regular health checkups and balanced nutrition can indirectly support faster clearance.
  
  

• Hydration & Diet: While you can’t “flush” THC overnight, staying well-hydrated helps maintain healthy kidney function and may keep you above cutoff thresholds. Eating a fiber-rich diet supports regular elimination, and antioxidant-packed foods (berries, leafy greens) help liver enzymes work efficiently.
  
  

• Exercise Habits: Light to moderate cardio can boost circulation and metabolism, aiding elimination. However, intense workouts shortly before a urine test can release stored THC from fat cells back into your bloodstream and urine, so if you’re close to testing, opt for gentle movement instead.

Full-Spectrum CBD and Trace THC Risks

Not all CBD products guarantee a THC-free experience. Full-spectrum extracts rely on small amounts of THC (up to 0.3%) to enhance therapeutic effects—a phenomenon known as the entourage effect. Those trace amounts can accumulate over weeks of regular dosing, triggering a positive urine or hair test. If you’re subject to surprise screenings or need absolute peace of mind, choose broad-spectrum or CBD isolate formulations, which remove virtually all THC.

Common Myths About THC Detox

Many “detox” tricks promise overnight results, but science tells a different story. Drinking massive amounts of water may dilute your urine below the cutoff, but labs often flag overly dilute samples for retesting. Activated charcoal and fake detox drinks can interfere with test chemistry, sometimes leading to inconclusive or invalid results rather than genuine negatives. Even saunas and vigorous sweat sessions offer only transient water weight loss, not accelerated metabolite elimination. In short, there’s no quick fix—time remains the only truly reliable detoxifier.

Practical Tips to Minimize Detection Risk

Plan your last THC use to allow sufficient clearance time: at least one week for occasional use, two to three weeks for moderate use, and 30 days or more if you’re a heavy consumer. On testing day, stay hydrated but avoid over-dilution; aim for pale yellow urine rather than water-clear. Maintain a balanced diet rich in fiber and antioxidants, which support liver health. Light exercise can help, but if you’re close to the cutoff, skip intense workouts that might temporarily release stored THC into your bloodstream.

Understanding Testing Thresholds and Cutoffs

Laboratories set specific ng/mL thresholds to distinguish heavy users from trace exposures. Urine initial screens often use a 50 ng/mL cutoff; confirmatory tests drop that to 15 ng/mL. Saliva and blood cutoffs vary more widely, so ask your testing provider for exact values. Hair panels typically screen at one pg/mg of THC-COOH, offering a stringent standard for long-term history.

Plan Ahead with At-Home Testing

Want extra assurance before a formal screening? Countrywide Testing’s at-home urine, saliva, and hair kits deliver lab-certified results in the privacy of your home. Discreet packaging and easy collection help you confirm your status—and adjust your timeline—long before you face that next test. 

Explore our full range of FDA-cleared drug test kits today and go into your screening with confidence.