How Long Does Weed Stay in Your System?

Cannabis detection windows vary enormously — from around 24 hours in saliva to 90 days in hair. For urine testing, the most common workplace method, an occasional user typically tests positive for about 3 days, while a daily user can test positive for 30 days or longer. The single biggest factor is frequency of use, because THC metabolites accumulate in body fat.

Why the ranges are so wide

Drug tests do not detect THC itself so much as THC-COOH, a metabolite the body produces as it processes THC. That metabolite is fat-soluble, so it stores in fatty tissue and releases slowly over time. Someone who uses daily builds a reservoir; someone who used once does not.

That is why published ranges look so inconsistent — they are describing genuinely different situations.

Typical detection windows

Urine (most common)

• Single use: roughly 1-3 days
• Occasional (2-3× per week): roughly 5-7 days
• Regular (4-6× per week): roughly 10-15 days
• Daily or near-daily: 30 days, sometimes considerably longer

Blood

Generally 1-2 days for occasional use, up to about a week for heavy use. Blood testing reflects recent use more closely, which is why it appears in impairment contexts.

Saliva

Around 24-72 hours in most cases. Saliva testing is increasingly used in roadside screening because it correlates better with recent consumption.

Hair

Up to about 90 days. Hair testing has a long window but is less reliable for light or infrequent use, and can be affected by external contamination.

What affects your personal timeline

• Frequency of use — by far the largest factor
• Body fat percentage — metabolites store in fat
• Metabolism — varies individually
• Dose and potency — more THC means more metabolites
• Hydration and the specific test threshold — different labs use different cutoffs

Things that do not reliably work

It is worth being straightforward here, because a lot of confident misinformation circulates.

• Detox drinks and kits — these generally dilute urine rather than remove metabolites. Many labs test for dilution and flag the sample.
• Drinking large volumes of water — same problem, and excessive intake carries its own health risks.
• Exercising immediately before a test — burning fat can actually release stored metabolites into the bloodstream, potentially raising levels short-term.
• Niacin, vinegar, cranberry juice — no reliable evidence.

Time and abstinence are what actually reduce metabolite levels.

An important caveat

Detection is not the same as impairment. A positive cannabis test can reflect use days or weeks earlier, long after any effects have worn off. This is a well-recognised limitation of current testing and a genuine source of unfairness in employment and roadside contexts.

If you face testing in a legal or employment context, the specific test, its cutoff threshold, and the applicable policy matter more than any general timeline. This article is general information, not legal or medical advice — consult a qualified professional about your specific situation.

Frequently asked questions

How long does weed stay in your urine?
Roughly 1-3 days after single use, and 30 days or more for daily users.

How long does weed stay in your blood?
Typically 1-2 days for occasional use, up to about a week for heavy use.

How long does weed stay in saliva?
Usually 24-72 hours.

Do detox drinks work?
They mostly dilute urine rather than remove metabolites, and labs commonly test for dilution.

Does exercise help me pass a drug test?
Not immediately before — burning fat can release stored metabolites and temporarily raise levels.

Does a positive test mean I am impaired?
No. Detection windows extend far beyond the period of any effects.

Do edibles stay in your system longer than smoking?
Effects last longer, and higher total doses can extend detection, but the metabolite is the same.