How long does weed stay in your system?

If you have cannabis in your system, it can be detected by a variety of drug tests. There are several factors that contribute to whether or not cannabis will show up on these tests, including the type of test you are taking, how frequently you use cannabis, and other biological factors.

Different testing methods

There are numerous ways to test a person for the presence of marijuana in their system. The different testing systems vary on the timeframe in which they can detect the metabolites of marijuana in the system.

Saliva test

The saliva test is viewed as a rapid detection test for traces of drugs and their corresponding metabolites. Marijuana is detectable for 34-48 hours after last use when taking the saliva drug test.

Urine Test

Urine test results depend on the frequency of marijuana use. For light users, tests may show positive results for 1-3 days after last use. Moderate users may show positive results for 7-21 days, and heavy users can show positive results for a month or longer after last use. This is the most common testing method since it is a quick, easy, and non-intrusive process.

Most urine tests can also detect the presence or absence of certain components that make up urine. This means that synthetic urine and the use of diluting products can be picked up, making these tests very reliable.

Hair test

For a hair drug test, a small hair sample is taken from the person’s head and screened for the presence of drugs. Light and moderate users are unlikely to yield positive test results through this testing method, but it is possible that traces may still show up. Heavy users can show results up to 90 days after last use. 

This test is most reliable for heavy users and can be more effective than urine tests, but hair treatments may affect the results. Although this test allows the detection of marijuana for a long period after last use, it will almost never detect a single use.

Blood test

Harvesting a blood sample is the best testing method to measure the concentration of drugs that are present in the system at the time of testing. If it is suspected that the person is actively under the influence of drugs, blood tests are the most effective in providing results. 

The downside of blood tests is the short window of opportunity, since drugs are rapidly metabolised. Marijuana is usually only detectable for 36 hours after last use. Results can take anywhere between a couple of minutes to several hours.

Do other factors affect your test results?

Other factors that may influence your test results include:

  • A high THC concentration in your marijuana
  • Frequency of marijuana use
  • Length of time since your last use
  • Your level of hydration
  • How quickly your system processes THC
  • Age, gender, and Body Mass Index (BMI)

Frequency of use is another important factor that will influence your test results. The general detection period for different user frequencies is as follows:

  • Single use – can be detected for up to 3 days
  • Moderate use (4 times a week) – can be detected for 5-7 days
  • Chronic use (every day) – can be detected for 10-15 days
  • Heavy chronic use (multiple times every day) – can be detected for up to 30 days

Short term effects of weed

The effects of smoking weed appear between 15 and 30 minutes, while edibles may take up to an hour or longer to kick in. 

The active ingredients in weed produce a short-term euphoric feeling or “high”. Common short term effects of weed include:

  • A relative sense of well-being
  • Mental and physical relaxation
  • Feeling that time goes by slower
  • General chattiness and improved social mood
  • An altered level of sensory perception
  • Increased appetite
  • A difference in coordination
  • Sleepiness or restlessness

High doses of weed may induce delusions, hallucinations, psychosis, or anxiety and paranoia (commonly referred to as a “bad high”).

When do short-term effects wear off?

The short-term effects of weed will usually start to wear off at around three hours, but this depends on the strength  of your weed as well as how much you have consumed. Some effects such as a hazy memory or sleepiness can last a few days.

There are no conclusive studies on the effects of using weed chronically, but the consensus is that some effects can become permanent, and it becomes more and more difficult to quit marijuana use.

How is weed broken down?

The main active ingredient in weed is known as Tetrahydrocannabinol (THC). When THC enters your body, it is absorbed into your bloodstream. Some THC will be stored temporarily, mostly in organs and fatty tissues. When it reaches the kidneys, THC can be reabsorbed into the bloodstream. THC is mostly broken down in the liver.

Drug tests look for the metabolites produced by consuming THC as they remain in your system for longer periods of time. These are eventually excreted in your stool and urine.

Getting weed out of the body

Your body needs time to break down THC and related metabolites. However, detoxification kits and masking are popular methods for those who attempt to pass a drug test.

Detoxification kits

Detoxification kits are mostly tailored towards those who are undergoing a urine test. These kits consist of adulterants like vinegar, goldenseal, niacin, vitamin C, or herbal extracts. However, these kits generally do not yield any results. They do not speed up your metabolism or promote the clearance of marijuana, so it is unlikely that detox kits will help you to pass a drug test.


Other common methods include urine masking. This involves adding chemicals like bleach or salt to the urine sample. Some also use urine samples that are not theirs (someone else’s urine or a synthetic sample). This method is unlikely to work since urine integrity tests can detect these masking agents. There is also the possibility that your sample will be tested for pH, temperature, gravity, colour, or dilution.

There is no foolproof way to cheat a drug test. Detox kits can contain harmful ingredients that cause mental and physical distress, and masking has a great potential for picking up altered samples.

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