How Long Does THC Stay in Your Body? Urine, Blood, Saliva & Hair (2026)

How long is THC detectable in urine, blood, saliva and hair? Science-based guide with realistic detection windows, key factors, detox myths and Swiss law.

How long does THC stay in your body? Tens of thousands of Swiss residents ask that question every year – before a roadside blood test, a workplace screening, or simply out of curiosity. The honest answer: it depends. On how much you consume, your metabolism, your body fat, the test type – and whether the lab looks for active Δ9-THC or its long-lived metabolite THC-COOH. This guide walks you through the science, gives realistic detection windows for urine, blood, saliva and hair, and dismantles the most stubborn detox myths.

Contents

1. Quick numbers
2. How the body processes THC
3. THC in urine
4. THC in blood
5. THC in saliva
6. THC in hair
7. Test method comparison
8. Factors that affect detection
9. Can you speed up THC clearance?
10. THC detection in Switzerland
11. 20 frequently asked questions

Quick numbers

How the body processes THC

THC (Δ9-tetrahydrocannabinol) is highly lipophilic – fat-loving. That single property explains why one joint can make you high for hours yet stay detectable for weeks.

1. Absorption

When smoked or vaped, THC crosses from the lungs into the blood within seconds. Peak plasma: 3–10 minutes. Edibles take 30–120 minutes but produce 11-hydroxy-THC in the liver – a more potent metabolite, which is why cookies often hit harder than a joint.

2. Distribution and storage

THC moves quickly from blood into well-perfused organs (brain, heart, liver) and then into fat tissue, where it accumulates and leaches back out over days to weeks. That is why daily users test positive weeks after quitting.

3. Liver metabolism

Cytochrome P450 enzymes (mainly CYP2C9 and CYP3A4) convert Δ9-THC into 11-OH-THC and finally into THC-COOH (11-nor-9-carboxy-THC). Only THC-COOH is psychologically inactive – but it is exactly what most urine tests screen for, because it sticks around the longest.

4. Elimination

About 65 % leaves via feces, roughly 20 % via urine. The terminal half-life of THC-COOH is ~1.3 days for occasional users and 5–13 days for chronic users.

THC in urine

The urine test is the world's most common drug test: cheap, non-invasive, long window. It measures the metabolite THC-COOH – usually via immunoassay with a cutoff of 50 ng/mL (screening) or 15 ng/mL (GC-MS confirmation).

The often-cited 77-day maximum comes from a study on heavy chronic users with high body fat (Ellis et al. 1985) – an extreme, not the norm. Realistic values for most chronic users are 3–6 weeks to a stable negative.

THC in blood

Blood tests target active Δ9-THC, which clears quickly – making them the go-to method for current impairment (traffic controls).

• Occasional use: 4–12 hours of active THC, metabolites up to 2–3 days
• Regular use: active THC up to 24 hours, metabolites up to 7 days
• Chronic use: measurable THC observed after 30 days of abstinence (Karschner et al. 2009)

THC in saliva

Saliva (oral-fluid) tests dominate roadside checks: easy sample, fast result, focused on recent use.

Passive exposure can trigger a short-lived positive only in extreme sealed-room situations. Normal exposure won't.

THC in hair

Hair analysis is cannabis's long-term memory. Hair grows ~1 cm per month, so a standard 3 cm sample covers ~90 days. Reputable labs use wash procedures to rule out external contamination. Single use is often not detectable.

Test method comparison

Factors that affect detection

• Frequency & dose – by far the biggest factor
• THC potency – modern genetics reach 15–28 % (see popular strains)
• Body fat – more fat = more storage
• Metabolism – genetic (CYP450 polymorphisms)
• Hydration – changes urine concentration, not total load
• Age & liver function
• Exercise – can transiently raise blood THC by mobilising fat stores
• Route of use – edibles yield more 11-OH-THC
• Test sensitivity – 20 vs 50 ng/mL cutoff changes results
• Sex – average higher body-fat in women can lengthen storage

Can you speed up THC clearance?

The detox industry is loud, the science is quiet: only your liver and time actually clear THC.

THC detection in Switzerland

Swiss traffic law applies a zero-tolerance approach with a measurement threshold of 1.5 µg/L THC in whole blood. Roadside saliva devices act as pre-screens; blood confirms. Workplace testing is only allowed for safety-relevant roles with clear cause. Cannabis in the FOPH pilot programmes (Basel, Zurich, Bern, Geneva…) is legal for registered participants but does not shield anyone from positive tests. More context: Is THC legal in Switzerland?

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20 frequently asked questions

1. How long does one joint stay in urine?

First-time use: usually 1–3 days, occasionally up to 7.

2. How long is THC detectable in blood?

Active Δ9-THC 4–12 h for occasional users; up to 30 days in extreme chronic users.

3. Can exercise clear THC faster?

Long-term yes (less fat); short-term exercise can release THC and raise blood levels.

4. Does drinking water help before a test?

Only short-term dilution – detectable by low creatinine. No real clearance.

5. Can CBD trigger a positive test?

Pure CBD, no. Full-spectrum products with legal < 1 % THC (Swiss limit) can at high doses.

6. How reliable are saliva tests?

Very reliable for recent use; useless for older use.

7. How long does THC stay in hair?

Up to 90 days. Single use often undetectable.

8. Does body fat matter?

A lot. More fat = longer window.

9. Can passive smoking trigger a positive?

Only in extreme enclosed environments.

10. Is everyone the same?

No. Genetic CYP2C9 variants alone can cause 2–3× differences.

11. What is THC-COOH?

THC's inactive main metabolite – the target of nearly all urine tests.

12. What is THC's half-life?

Δ9-THC: 20–36 h in occasional users; THC-COOH: 3–13 days in chronic users.

13. What does a 50 ng/mL cutoff mean?

Values below count as negative; GC-MS confirmation drops the cutoff to 15 ng/mL.

14. Can I wait 24 h and pass a blood test?

Occasional user: often yes. Daily user: almost never.

15. Do medications affect THC clearance?

Yes – rifampicin and St John's wort speed it up, ketoconazole slows it down.

16. Why do I still test positive after days without use?

THC-COOH leaches from fat over 3–6 weeks in daily users.

17. Does a positive urine test prove impairment?

No. Only blood ≥ 1.5 µg/L Δ9-THC does.

18. Test in a few days – what should I do?

Stop, move, eat well. No miracles.

19. When do I become chronically detectable?

After weeks of daily use.

20. Where is trustworthy Swiss info?

The FOPH (BAG), plus our law and THC status guides.

Conclusion

There is no single answer to "how long does THC stay in the body" – but a clear map: blood & saliva show current use, urine shows the past days-to-weeks, hair the past months. Consume responsibly, know your limits, never drive impaired – and knowledge will always beat miracle cures.