THC from a blunt typically stays detectable in urine for 3 to 10 days after smoking, depending on how often you use. If you only smoked once, you’re looking at 3 to 4 days on a standard drug test. If you smoke regularly, that window stretches to around 10 days, and in some cases up to 21 days with more sensitive testing.
Those ranges depend on the type of test, the cutoff level it uses, and how much THC your body has stored. Here’s what actually matters for each scenario.
Why THC Lingers Longer Than Other Drugs
Most drugs dissolve in water, get processed by your kidneys, and leave relatively quickly. THC works differently. It’s fat-soluble, meaning your body pulls it out of the bloodstream and tucks it into fat cells. Your liver breaks THC down into over 80 different byproducts, and the one drug tests look for is a compound called THCA (sometimes written as THC-COOH). This byproduct sticks around much longer than the THC that actually gets you high.
What makes THC especially persistent is a recycling loop between your liver and intestines. After your liver processes THC byproducts, some get sent to your gut through bile, reabsorbed into your bloodstream, and sent right back to the liver again. This cycle extends the time it takes your body to fully clear everything out. The more often you smoke, the more THC accumulates in fat tissue, and the longer this recycling process takes to wind down.
Urine Test Detection Windows
Urine testing is by far the most common method for employment and court-ordered screening. The standard cutoff is 50 ng/mL, which is the threshold most workplace tests use. Some tests use a lower, more sensitive cutoff of 20 ng/mL. The cutoff matters a lot for your timeline.
At the standard 50 ng/mL cutoff:
- One-time or occasional use: 3 to 4 days after smoking
- Regular or chronic use: up to 10 days after your last session
At the more sensitive 20 ng/mL cutoff:
- One-time or occasional use: up to 7 days
- Regular or chronic use: up to 21 days
If you’re facing a pre-employment drug screen, it almost certainly uses the 50 ng/mL initial cutoff. If that screening comes back positive, a confirmatory test is run at an even lower threshold of 15 ng/mL, specifically targeting THCA. So a borderline result on the initial screen could still be confirmed positive.
Oral Fluid and Blood Tests
Oral fluid (saliva) tests are becoming more common, especially for roadside screening and some workplace programs. These tests look for THC itself rather than the longer-lasting byproducts, so the detection window is much shorter. The initial screening cutoff for oral fluid is 4 ng/mL, with a confirmatory cutoff of 2 ng/mL. THC is generally detectable in saliva for 24 to 72 hours after smoking.
Blood tests also detect THC directly. THC levels in blood spike within minutes of smoking and drop off quickly, usually becoming undetectable within a few hours for occasional users. For heavy users, low levels can persist longer because fat tissue slowly releases stored THC back into the bloodstream. Blood testing is most often used in DUI investigations or hospital settings, not typical employment screening.
Hair Follicle Tests
Hair testing has the longest detection window of any method: up to 90 days. As your hair grows, traces of drug byproducts get deposited into the hair shaft. Since head hair grows roughly half an inch per month, a standard 1.5-inch sample cut at the scalp covers about three months of history. The collector takes 90 to 120 strands, so very short hair can limit what the test captures.
Hair tests are less common for routine employment screening but show up in certain industries and legal situations. They’re better at detecting patterns of repeated use than a single smoking episode, since one-time use sometimes doesn’t deposit enough byproducts to trigger a positive result.
What Affects Your Personal Timeline
The biggest factor is frequency of use. Someone who smoked a single blunt at a party is in a completely different situation than someone who smokes several times a week. Chronic use means more THC has accumulated in your fat cells, and your body needs significantly more time to clear it all out.
Body fat percentage plays a role too. Since THC is stored in fat tissue, people with higher body fat may retain detectable levels somewhat longer. Metabolism, hydration, and overall health also influence how quickly your body processes and eliminates THC byproducts, though these factors are harder to quantify or control in any meaningful way.
Does Exercise or Detox Speed Things Up?
You’ll find plenty of products and strategies marketed as THC detoxes. The reality is more modest. Exercise can slightly raise THC levels in the blood for a short time, since burning fat releases stored THC back into circulation. In studies, a 45-minute workout temporarily bumped blood THC levels, but they dropped back down within a couple of hours. Importantly, for urine tests, exercise didn’t cause significant changes in THC concentration.
This means exercising in the days leading up to a test is unlikely to hurt you, but it also won’t dramatically flush THC from your system faster than your body would clear it on its own. Drinking large amounts of water can dilute your urine temporarily, but testing labs check for dilution and may flag or reject an overly diluted sample. There’s no reliable shortcut that overrides the biological timeline your body is working on.
Quick Reference by Test Type
- Urine (standard cutoff): 3 to 4 days for occasional use, up to 10 days for chronic use
- Urine (sensitive cutoff): up to 7 days occasional, up to 21 days chronic
- Saliva: 24 to 72 hours
- Blood: a few hours to a couple of days
- Hair: up to 90 days