If you smoked one blunt and don’t use cannabis regularly, THC will typically clear your system within 1 to 6 days for a urine test, depending on the test’s sensitivity. The exact window varies by the type of test, how much THC was in the blunt, and your body composition. Here’s what the research says for each testing method.
Urine Test Detection: 1 to 6 Days
Urine tests are by far the most common drug screening method, and the detection window for a single use depends heavily on the cutoff level the lab uses. Federal workplace drug tests screen at a 50 ng/mL cutoff for the initial test, with a confirmatory threshold of 15 ng/mL. At the standard 50 ng/mL cutoff, a single session of cannabis use is detectable for only about 1 to 2 days. That’s a narrow window, and many one-time users will test negative within 48 hours.
At a more sensitive 20 ng/mL cutoff, which some employers and legal programs use, detection stretches to 1 to 5 days after a lower-dose session and 3 to 6 days after a higher dose. A blunt typically contains more cannabis than a joint, so if the blunt was packed with high-potency flower, your detection window is likely on the longer end of that range.
What urine tests actually detect isn’t THC itself but a metabolite your liver produces when it breaks down THC. This metabolite has an elimination half-life of roughly 30 hours in studies using a one-week collection period, and possibly closer to 44 to 60 hours when measured over two weeks. That means it takes about 1 to 2.5 days for your body to clear half of the metabolite, then another cycle to halve what remains, and so on. For a single blunt, most of it is gone within a few days.
Blood and Saliva Tests
Blood tests measure active THC rather than its metabolite, so the detection window is much shorter. After a single use, THC in blood drops rapidly within hours as it redistributes into tissues. For an infrequent user, blood levels typically fall below detectable limits within 12 to 24 hours, though trace amounts could linger slightly longer. Federal oral fluid testing uses a cutoff of 4 ng/mL for THC on the initial screen and 2 ng/mL for confirmation. Saliva tests generally detect cannabis for 24 to 72 hours after a single use, making them more of a “recent use” indicator than a long-term one.
Hair Tests Are Less of a Concern
Hair follicle tests can theoretically look back 90 days, but they are notably poor at catching one-time or infrequent cannabis use. Research confirms that hair testing is less sensitive than urine testing for detecting sporadic cannabis exposure, and it remains unclear whether standard lab procedures can reliably identify traces from a single intake. If your only exposure was one blunt, a hair test is unlikely to flag it, though it’s not impossible.
Why THC Lingers in Your Body
THC is highly fat-soluble. When you inhale it, your body absorbs it quickly and shuttles it into fat cells for storage. From there, it slowly leaks back into your bloodstream and gets processed by your liver into the metabolite that shows up on urine tests. This passive diffusion from fat is why THC has such a long elimination timeline compared to water-soluble drugs like alcohol.
For a one-time user, only a small amount gets deposited into fat, so the clearance process is relatively quick. Chronic daily users, by contrast, accumulate so much THC in their fat tissue that they can test positive for weeks. Some heavy users have tested positive at the 20 ng/mL level after 77 days of abstinence.
Factors That Speed Up or Slow Down Clearance
Your body fat percentage matters. Since THC parks itself in fat cells, people with more body fat have more storage capacity for the drug, which can slow elimination. People with less body fat and faster metabolisms tend to clear THC more quickly. Hydration plays a minor role: well-hydrated people produce more dilute urine, which can push metabolite concentrations below the test cutoff on a given day, but drinking excessive water can make a sample look suspicious to the lab and trigger a retest.
Exercise is a double-edged sword. Working out burns fat, which sounds helpful, but research shows that breaking down fat cells actually releases stored THC back into the bloodstream. In studies with regular cannabis users, exercise caused a temporary spike in blood THC levels rather than flushing it out. For someone who smoked one blunt, this effect is minimal since there’s very little THC stored. But if you’re close to a test date, intense exercise right beforehand could theoretically nudge your levels up rather than down.
The potency of the blunt also matters. A blunt rolled with high-THC flower delivers a larger dose, and studies show that higher doses produce longer detection windows at every cutoff level. A blunt with lower-potency cannabis or one that you only partially smoked would fall on the shorter end of the detection ranges.
Realistic Timelines by Test Type
- Urine (50 ng/mL cutoff): 1 to 2 days
- Urine (20 ng/mL cutoff): 3 to 6 days
- Blood: 12 to 24 hours
- Saliva: 24 to 72 hours
- Hair: Up to 90 days in theory, but a single blunt is unlikely to be detected
These ranges assume you are not a regular cannabis user. If you smoke even a few times per week, THC accumulates in fat stores and the numbers shift considerably. For a true one-time exposure from a single blunt, most people will test clean on a standard urine screen within 3 to 4 days, and often sooner.