◆ Buying guide
Cannabis and Drug Tests: How Long It Really Stays Detectable
· 7 min read
Drug tests do not look for THC. They look for **THC-COOH**, an inactive metabolite that is fat-soluble and therefore hangs around long after any effect has gone. That single fact explains almost everything about detection windows — including why frequency matters far more than dose, and why the honest answer is always a range.
The windows, honestly
| Test | What it detects | Typical window |
|---|---|---|
| Urine (most common) | THC-COOH metabolite | Single use: 1–3 days · Occasional: 3–7 · Daily: 10–30+ days |
| Blood | Active THC | Hours to about 2 days; longer in very heavy users |
| Saliva | Recent active THC | Up to about 24–72 hours |
| Hair | Metabolites in the shaft | Up to about 90 days, and unreliable at low use |
What actually moves the number
- How often you use. By a distance the largest factor.
- Body fat. THC-COOH is stored in fat and released slowly, so body composition genuinely changes the timeline.
- Metabolism and hydration. Real but modest effects, and heavy dilution is itself detectable.
- The test's cut-off. 50 ng/mL is standard for urine; a 20 ng/mL screen is meaningfully stricter and lengthens the window.
- Method of use. Edibles and inhalation produce different peak concentrations, though both leave the same metabolite behind.
The practical position
Time is the only thing that reliably works, and the amount of time depends on how often you have been using rather than on what you took last. If you know a test is coming, stopping earlier is the whole strategy — there is no shortcut worth the risk of a flagged sample.
Worth being clear about the legal side: in most of the United States an employer may test and may act on a positive result regardless of whether cannabis is legal where you live. Legality and employment policy are separate questions, and a handful of states restrict off-duty testing while most do not. If your job depends on this, check your own state and your own contract rather than a general article.
Frequently asked questions
- How long does cannabis stay in your system?
- For a urine test: roughly 1–3 days after a single use, 3–7 for occasional use, and 10–30 days or more for daily use. Blood is hours to about two days, saliva up to about three days, and hair up to about ninety.
- Why does frequency matter more than how much I took?
- Tests look for THC-COOH, a fat-soluble metabolite that accumulates in body fat and is released slowly. Regular use builds a store; a single large dose does not. That is why a daily user clears far more slowly than an occasional one.
- Do detox drinks work?
- Not in the way they are sold. Nothing you drink removes a fat-soluble metabolite from fat — where they appear to work, it is by dilution, and labs test for dilution directly via creatinine and specific gravity. A diluted sample is often treated as a failure.
- Does exercise help before a test?
- It can make things worse. Burning fat mobilises stored metabolites into the bloodstream, which can raise a reading in the short term. Heavy exercise in the day or two before a test is the opposite of helpful.
- What is the cut-off on a urine test?
- 50 ng/mL is the common standard. Some employers use a stricter 20 ng/mL screen, which lengthens the detection window considerably for the same person and the same usage.
- Can I be tested if cannabis is legal where I live?
- In most of the United States, yes. Employment policy and legality are separate questions — a handful of states restrict off-duty testing, most do not. Check your own state and your contract rather than assuming legality protects you.
Keep reading