Updated on December 2o, 2025
Written by: Ahsan Riaz
Reviewed by: Dr. Diana Rangaves, PharmD, RPh — Pharmacist, Medical Writer, and Author
If you smoke cannabis once a week, most urine drug tests turn negative within 3–7 days. Blood tests usually clear within 1–2 days, saliva tests within 1–3 days, while hair tests can detect use for up to 90 days. Exact timing depends on metabolism, body fat, and THC potency.
THC Detection Chart
This chart shows average THC detection windows and key factors influencing clearance for weekly cannabis users.
Average THC Detection Times for Weekly Cannabis Users
| Test Type | Detection Window |
|---|---|
| Urine | 3–7 days |
| Blood | 1–2 days |
| Saliva | 1–3 days |
| Hair | Up to 90 days |
This table gives a clear snapshot of how long THC metabolites can be detected in different tests, depending on individual factors like metabolism and body composition.
How THC Metabolizes in Your Body
According to toxicology research published by the National Institutes of Health (NIH), THC is metabolized into THC-COOH, a fat-soluble compound that remains detectable long after intoxication ends. When you smoke cannabis, THC (tetrahydrocannabinol) enters your bloodstream within seconds. It spreads through the body and quickly binds to fat tissue. From there, the liver converts THC into THC-COOH, a fat-soluble metabolite.
This metabolite is the real reason drug tests stay positive after the high is gone.
THC-COOH slowly leaks out of fat cells over time and is eliminated mainly through urine. Because fat storage and metabolism differ from person to person, THC never leaves the body at a fixed speed.
THC Half-Life by Use Pattern
- Single use: about 1–2 days
- Weekly use: about 2–4 days
- Chronic use: up to 14 days or more
This explains why two people with the same smoking habit can get very different test results.
Real-World Example (Why Results Vary)
John weighs 180 lbs and exercises several times a week. After smoking once weekly, he tested negative on a urine test in 5 days.
Sarah weighs 150 lbs but has a higher body-fat percentage and little physical activity. With the same usage pattern, she tested positive for 7 days.
Detection Windows Explained (By Test Type)
Urine Test
Urine testing is the most common cannabis screening method. It does not detect active THC. It detects THC-COOH, the stored metabolite.
For weekly users, urine tests usually turn negative within 3–7 days. Chronic users may remain positive for several weeks.
Most urine drug panels use a 50 ng/mL cutoff, meaning small trace amounts below that level are considered negative. This is why dilution tricks rarely work consistently—labs check urine concentration, color, and creatinine levels.
You can feel completely normal and still test positive because urine tests measure past exposure, not impairment.
Blood Test
Blood tests detect active THC, not stored metabolites. THC peaks quickly after smoking and drops fast as the body metabolizes it.
For weekly users, blood tests are usually negative within 1–2 days.
Because of this short window, blood testing is mainly used in legal or medical situations where recent use matters.
Blood tests are poor indicators of long-term or occasional cannabis use.
Saliva Test
Saliva tests detect THC residue from the mouth and very recent bloodstream presence.
The typical detection window is 1–3 days. Potency, frequency, and oral hygiene can influence results slightly.
A positive saliva test almost always means recent intake, not THC stored from earlier in the week.
Hair Follicle Test
Hair testing has the longest detection window, up to 90 days.
As hair grows, THC metabolites become embedded in the hair shaft. Longer hair can reflect a longer history of use. Unlike urine or blood tests, hair testing is not affected by hydration, metabolism, or short-term detox attempts.
Hair tests are uncommon for casual weekly users and are mostly used for employment screening or legal monitoring.
Detection vs Impairment: Why Feeling Sober Isn’t Enough
One of the biggest misunderstandings around cannabis testing is confusing sobriety with clearance.
You can feel completely sober while THC-COOH is still detectable in urine. Drug tests do not measure how you feel. They measure chemical traces left behind after your body processes THC.
This distinction explains why many weekly users fail tests despite not feeling impaired at all.
What Actually Affects THC Clearance
Metabolism plays a major role. Faster metabolism generally means faster elimination.
Body fat percentage matters because THC is fat-soluble. More fat equals more storage.
Frequency of use separates weekly users from chronic users. Even small increases in frequency can extend detection times.
THC potency and strain influence how much metabolite builds up.
Hydration and diet support liver and kidney function but don’t create instant results.
Exercise helps over time by burning fat, slowly releasing stored THC.
Liver and kidney health directly affect how efficiently THC is processed and excreted.
Two weekly users can differ by several days purely because of lifestyle and body composition.
Natural THC Clearance: What Actually Helps
Consistent hydration supports normal elimination.
Moderate exercise helps over time.
Balanced nutrition supports detox organs.
Extreme detox products don’t change biology.
Time remains the most powerful factor.
Anything promising “instant clean” should be treated with skepticism.
Summary Table by Use Frequency
| Use Frequency | Urine | Blood | Saliva | Hair |
|---|---|---|---|---|
| Single use | 1–3 days | 1–2 days | 1–2 days | Up to 90 days |
| Weekly | 3–7 days | 1–2 days | 1–3 days | Up to 90 days |
| Daily | 15–30 days | 1–2 days | 1–3 days | Up to 90 days |
Key Takeaways
- Smoking once a week usually means urine tests clear in 3–7 days
- Feeling sober does not equal testing clean
- THC stays longer in people with higher body fat
- Detox drinks don’t remove stored THC
- Time and metabolism matter more than tricks
FAQs
Can I pass a urine test if I smoke once a week?
In most cases, yes. People who smoke cannabis about once a week usually test negative on a urine drug test within 3–7 days. Urine tests do not detect active THC; they detect THC-COOH, a metabolite stored in fat tissue. How quickly this metabolite clears depends on metabolism, body fat percentage, hydration, and THC potency. Someone with higher body fat or slower metabolism may remain positive closer to the 7-day mark, while others may clear sooner.
Does exercise help speed up THC clearance?
Exercise can help indirectly, but it is not a quick fix. Because THC is stored in fat cells, moderate and consistent exercise can help burn fat over time, which slowly releases THC-COOH into the bloodstream for elimination. However, intense exercise right before a test does not guarantee faster clearance and may temporarily increase metabolite levels. Long-term activity habits matter far more than last-minute workouts.
Do detox drinks actually work?
Most detox drinks do not remove THC from the body. They typically work by diluting urine temporarily, which labs often detect by checking creatinine levels, urine color, and specific gravity. THC-COOH stored in fat cannot be flushed out instantly. Natural metabolism, time, and healthy organ function are far more reliable than products promising “same-day” results.
How does body fat affect THC detection time?
THC is fat-soluble, meaning it binds to fat tissue and is released slowly over time. People with higher body fat percentages tend to store more THC-COOH, which can extend urine detection windows by several days. This is one of the main reasons two people with the same smoking frequency can receive different drug test results.
Is feeling sober the same as being test-clean?
No. Feeling sober only means the psychoactive effects of THC have worn off. Drug tests look for chemical traces, not impairment. THC-COOH can remain detectable in urine long after you feel completely normal. This is why many weekly users are surprised by positive results even when they feel fine.
What is the half-life of THC?
The half-life of THC refers to how long it takes for half of the substance to leave the body. For occasional or weekly users, THC’s half-life is typically 2–4 days, while chronic users may have a half-life of up to 14 days. Because THC accumulates in fat, complete elimination takes multiple half-life cycles, not just one.
Are hair follicle tests more reliable than urine tests?
Hair tests are reliable for detecting long-term cannabis use, but they are not commonly used for weekly or casual users. These tests can detect THC metabolites for up to 90 days because the metabolites become embedded in growing hair. Hair testing is less affected by hydration or metabolism and is usually reserved for employment screening or legal monitoring.
What’s the difference between occasional and chronic cannabis use?
Occasional or weekly users do not build up large stores of THC-COOH in fat tissue, so their detection windows are much shorter. Chronic users smoke frequently enough that metabolites accumulate faster than the body can eliminate them. This leads to longer detection times, sometimes lasting weeks even after stopping use.
Can diet or hydration significantly change drug test results?
Healthy hydration and a balanced diet support liver and kidney function, which helps natural THC elimination. However, they do not dramatically shorten detection times. Overhydration before a test may raise red flags during lab analysis. Consistency over time matters more than short-term dietary changes.
Why do some people test positive longer than expected?
Extended detection times are usually caused by a combination of factors: higher body fat, slower metabolism, frequent or high-potency use, genetics, and overall health. Even among weekly users, these variables can create differences of several days in urine test results. This variation is normal and well-documented in toxicology research.
Conclusion
For most people who smoke once a week, THC clears urine within 3–7 days. Blood and saliva tests usually turn negative much sooner, while hair tests can reflect use for up to 90 days.
The key isn’t guessing or panicking. It’s understanding how THC is stored and eliminated. Metabolism, body fat, and frequency explain nearly all variations in test results. Time—not detox myths—is what actually works.
When you understand the science, the stress drops away.
References
- National Institute on Drug Abuse (NIDA) – Marijuana Drug Testing
- CDC – Cannabis and Health Effects
- Healthline – How Long Does Weed Stay in Your System?
Further information
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.