How Long Does Cannabis Stay in Your System? Detection Times by Test Type

Key Takeaways

• Detection is not impairment. Testing looks for evidence of cannabis exposure, not intoxication — urine in particular can flag use long after any effect has ended. You can be completely sober and still fail.
• Frequency is usually the most important practical factor. An occasional user often clears a urine test in a few days; a daily user can stay positive for weeks after stopping.
• Commonly cited ranges: urine from several days to 30 days or more depending on use; blood and saliva generally hours to a few days; a standard scalp-hair sample often covers roughly 90 days.
• Edibles can extend the urinary window. A 2026 systematic review found oral doses produced longer-lasting urinary metabolite elevation than inhaled ones.
• Nothing reliably speeds it up. Detox drinks and kits are unreliable, and some are unsafe.

Detection Isn't the Same as Being High

This is the thing that trips people up, so it's worth putting first: a drug test is not a sobriety test.

THC is highly fat-soluble, so after use it distributes into fatty tissue. From there it's released and metabolised gradually, which is what drives the prolonged excretion of 11-nor-9-carboxy-THC (usually shortened to THC-COOH) in urine — especially after regular use. THC-COOH is the compound most urine testing looks for, and it is not psychoactive. It's a leftover.

That's the whole reason the numbers in this article are so much longer than the numbers in our guide on how long a high lasts. The high is over in hours. The chemical evidence sticks around far longer. Someone who last used cannabis three weeks ago is in no sense impaired, and can still fail a urine screen.

The reverse is also true and less appreciated: someone can be genuinely impaired right now and pass a hair test, because hair reflects use over months rather than this afternoon.

What Each Test Actually Measures

These four don't all look for the same compound, and that's most of the reason their timelines differ so much:

• Urine primarily looks for THC-COOH, the inactive metabolite. It can identify past exposure long after any impairment has ended, which is why its window is much longer than those of blood or saliva.
• Blood usually measures THC itself, often alongside metabolites. It's more closely associated with recent use — though a given concentration doesn't reliably establish impairment.
• Saliva generally looks for THC, much of it simply left in the mouth after cannabis is smoked or vaporised. Hence a relatively short window.
• Hair may be tested for THC and related cannabinoids, sometimes including THC-COOH. It can show exposure over months, but contamination and interpretation are considerably more complicated than the familiar 90-day figure suggests.

So "how long does cannabis stay in your system" doesn't have one answer. It has four, depending on what's being sampled.

Urine: The Long Tail

Urine testing is the most common workplace method, and it has the widest spread of outcomes. The commonly cited ranges look roughly like this:

• Single or occasional use: around 3 days, sometimes up to a week
• Several times a week: roughly 5 to 10 days
• Daily or near-daily use: approximately 10 to 30 days or longer

Treat those as orientation, not a schedule. The spread between individuals is genuinely large.

There's also a threshold question most articles skip, and it's a two-stage process. Under the US federal workplace system, the initial urine immunoassay cutoff for marijuana metabolites is 50 ng/mL. A sample that screens positive is then re-tested by a more specific confirmatory method, using a cutoff of 15 ng/mL for THC-COOH. Other countries, employers and testing programmes may use different procedures and cutoffs entirely.

The most useful recent evidence here is a 2026 systematic review that pooled 92 studies of urinary THC metabolite concentrations (McCartney et al., 2026, Pharmacological Research). Three findings stand out:

• Low doses can reach the confirmatory cutoff. Single doses of just 1 to 5 mg of THC — and repeated doses under 1 mg a day — sometimes produced urinary concentrations above the 15 ng/mL confirmatory cutoff, particularly after oral use. The review describes the evidence at these very low doses as limited and inconsistent, and exceeding 15 ng/mL in a study isn't the same as producing a positive workplace result, since a sample generally must first screen positive at 50 ng/mL.
• Regular users can stay positive for weeks. People using weekly to daily could remain above that threshold for weeks after they stopped.
• Route matters. Oral ingestion produced prolonged elevation compared with inhalation.

That last point is worth sitting with if you use edibles: the same milligrams, eaten rather than inhaled, can leave a longer detectable trail.

Blood, Saliva, and Hair

Blood has a short window — commonly a matter of hours up to a day or two for occasional users, though heavy regular users can test positive for longer. Because it measures THC itself, it's the matrix most often used where recent use is the question, such as after a crash. Even here, though, detection isn't impairment: THC can persist after its noticeable effects have ended, especially in regular users, and no blood concentration functions like the familiar alcohol limit.

Saliva (oral fluid) is typically detectable for around 24 hours in occasional users, stretching toward 72 hours with regular use — but route matters enormously here, because a lot of what's detected is THC left in the mouth. Smoked or vaporised cannabis is far easier to pick up than a swallowed dose. In one randomised crossover study, 20 adults took an oil containing 10 mg of THC and 200 mg of CBD orally; half an hour later, the two roadside point-of-collection devices returned positive results for only 25% and 50% of participants respectively, and by 10 hours every participant tested negative (Suraev et al., 2024, Drug Testing and Analysis). That's a small single-dose study of one formulation and two specific devices — but it shows how badly a universal "saliva window" travels across routes. Oral fluid is used for roadside testing precisely because the window is short.

Hair is the outlier. A standard scalp-hair sample typically covers roughly 90 days — a figure that reflects the length of hair laboratories usually analyse rather than a biological ceiling. Cannabinoids can enter growing hair from the bloodstream, and may also reach it through sweat, sebum, and external contamination — which makes hair results more complicated to interpret than urine results. Worth knowing too: hair testing is much better at picking up consistent, regular use than occasional use, and light users are more likely to be missed.

What Actually Changes Your Timeline

In rough order of how much they matter:

• How often you use. Usually the most important practical factor. Regular use lets THC accumulate in fatty tissue through repeated exposure, which is why the detection window is often measured in weeks rather than days.
• How much, and how strong. Higher doses and higher-THC products extend things.
• How you take it. Oral routes tend to leave a longer urinary trail than inhaling — see our comparison of the different consumption methods.
• Body composition. Because THC is stored in fat, body composition may contribute — but it can't be used to predict an individual detection window reliably.
• Your individual metabolism. Real, but usually less decisive than people hope.

Notice what isn't on that list: anything you can do the night before.

Can You Speed It Up?

Short answer: not reliably.

Time is the mechanism. Your body has to release and metabolise what's stored in fatty tissue, and there's no consumer product that meaningfully accelerates that. The detox drinks, pills and kits sold for this purpose are unreliable — and some carry their own risks, whether from aggressive diuretics, extreme water loading, or simply being unregulated products making unverifiable claims.

The two things people ask about most:

• Drinking lots of water doesn't remove metabolites; at most it dilutes a sample, and labs specifically check for that. A dilute sample may trigger additional scrutiny or a recollection, depending on the testing policy.
• Exercise is more complicated than the folklore suggests. Because THC can remain stored in fatty tissue, researchers have looked at whether exercise releases some of it back into circulation. A small study in regular users found a brief rise in blood THC after exercise, but no significant rise in THC-COOH — so it doesn't show that exercise changes whether someone passes a urine test, in either direction.

If a test matters, the only dependable variable is how much time has passed since you last used.

Frequently Asked Questions

How long after one joint will I pass a urine test? For someone who uses rarely, commonly cited ranges put it around 3 days, occasionally up to a week. But cutoffs, dose and individual variation all move that, so treat it as a rough guide.

Do edibles stay in your system longer than smoking? The urinary trail can be longer, yes. A 2026 review of 92 studies found oral doses produced more prolonged elevation of urinary metabolites than inhaled ones.

Can secondhand smoke make me fail? It's possible under extreme conditions — prolonged exposure in a small unventilated space — but under realistic conditions it very rarely produces a positive at standard cutoffs.

Does CBD show up on a drug test? CBD itself isn't what tests look for. But full-spectrum CBD products may contain trace THC, and with regular use that can accumulate enough to trigger a positive. Broad-spectrum or isolate products are lower-risk — though mislabelled or contaminated products mean neither guarantees a negative result.

Why can I be sober and still fail? Because urine testing measures an inactive breakdown product, not impairment. It indicates THC exposure at some point within the detection window — nothing more.

The Bottom Line

There's no single number, and anyone offering one is simplifying. What the evidence supports is a pattern: blood and saliva reflect recent use over hours to a couple of days, urine reflects the past several days to several weeks depending mostly on how often you use, and hair reflects months — with more interpretive complications than its 90-day reputation implies. Frequency is the biggest lever, and route matters more than people expect: edibles can leave a longer urinary trail than inhaling. Nothing reliably shortens the window, so if a test is coming, time is the only thing that genuinely helps. And it's worth repeating the point that causes the most confusion and unfairness: a confirmed positive urine result indicates THC exposure sometime within the preceding days or weeks. It does not show that you were impaired at work — or even establish exactly when the exposure occurred.

This article is for informational purposes only and isn't legal or medical advice. Testing policies, cutoffs, and cannabis laws vary widely by employer and location — check what applies to you.

Last updated: August 2026 | Based on: a 2026 systematic review of urinary THC metabolite concentrations and a 2024 oral-fluid detection trial from DeepWeed's knowledge base, plus commonly cited clinical detection ranges.