How Long Does Weed Stay in Your System?
Quick Answer
THC is detectable in urine for 3–30 days depending on usage frequency. In blood, 1–2 days for occasional users. In hair, up to 90 days.
Typical Duration
Quick Answer
THC (the active compound in marijuana) stays in your system for different lengths of time depending on the test type and how often you use it. Urine tests detect THC for 3–30 days, blood tests for 1–7 days, saliva tests for 1–3 days, and hair tests for up to 90 days.
Detection Windows by Test Type
Urine Test (Most Common)
- Single use: 3–4 days
- Moderate use (4x/week): 5–7 days
- Daily use: 10–15 days
- Heavy daily use: 30+ days
Blood Test
- Occasional use: 1–2 days
- Regular use: 3–7 days
- THC enters the bloodstream within seconds of inhalation
Saliva Test
- Occasional use: 1–3 days
- Chronic use: up to 29 days (rare)
- Increasingly used in roadside testing
Hair Follicle Test
- Detection window: up to 90 days
- Tests a 1.5-inch hair sample closest to the scalp
- Less reliable for infrequent users
Factors That Affect Detection Time
Frequency of use is the biggest factor. THC is fat-soluble and accumulates in fat tissue with repeated use, taking longer to fully clear.
Body fat percentage matters because THC metabolites are stored in fat cells. People with higher body fat may retain THC longer.
Metabolism — a faster metabolism breaks down THC more quickly. Exercise, age, and overall health affect metabolic rate.
Potency and dose — higher-THC products produce more metabolites that take longer to clear.
Method of consumption — edibles are metabolized differently than smoking and may produce metabolites that linger longer.
Hydration — while water doesn't speed up THC elimination, severe dehydration can concentrate urine and affect test results.
How THC Is Metabolized
When you consume cannabis, your liver converts THC into metabolites, primarily THC-COOH. This metabolite is what most drug tests detect. THC-COOH is fat-soluble, meaning it's stored in fat cells and slowly released back into the bloodstream over time. This is why detection windows are much longer for frequent users — more THC-COOH has accumulated in fat tissue.
Common Drug Test Cutoff Levels
| Test Type | Standard Cutoff |
|---|---|
| Urine (immunoassay) | 50 ng/mL |
| Urine (confirmation/GC-MS) | 15 ng/mL |
| Blood | 1–5 ng/mL |
| Saliva | 25 ng/mL |
| Hair | 1 pg/mg |
Tips for Faster Clearance
- Time is the only reliable method — no supplement or detox drink is scientifically proven to speed elimination
- Stay hydrated and eat a healthy diet
- Exercise regularly (but not right before a test, as it can temporarily release stored THC)
- Avoid further use to stop adding to the accumulation
Pro Tips
Time is the only reliable way to clear THC — detox drinks and supplements are not scientifically proven to speed elimination.
— SAMHSA
If you know a test is coming, stop using as early as possible; frequency of use is the single biggest factor in how long THC stays detectable.
— HowLongFor Editorial Team
Avoid intense exercise in the 24 hours before a urine test, since it can temporarily release stored THC and raise your reading.
— Mayo Clinic
Quick Facts
THC-COOH is fat-soluble and accumulates in fat cells, which is why heavy daily users can still test positive more than 30 days after their last use.
Source: SAMHSA
Hair follicle tests can detect cannabis use for up to 90 days, but they are unreliable for infrequent users and can be affected by environmental exposure.
Source: American Association for Clinical Chemistry
Exercising shortly before a urine test can temporarily raise THC levels by releasing metabolites stored in fat tissue.
Source: Mayo Clinic