How Long is THC Detectable? (Blood, Urine, Hair)

The substance tetrahydrocannabinol, THC for short, is extracted from the hemp plant and is the main active ingredient in cannabis – THC gives hashish and marijuana an intoxicating effect. For easy use, you can find it in multiple strains, including Kurvana’s northern lights strain. THC drug test takes advantage of the relatively long detectability of this cannabis compound.

How long THC can be detected depends on various factors.

THC Detectability

The intoxicating effects of smoked cannabis last anywhere from one to four hours. When consumed orally, the effect usually wears off after a maximum of ten hours. But even when the intoxicating effect wears off, there may still be THC residues in the body that can be detected by a drug test.

Various drug tests are used to detect THC and its breakdown products. For example, rapid THC tests with test strips are used in traffic controls. If the amount measured is above a particular value, the so-called cut-off, then drug use can be assumed. Laboratory methods such as gas chromatography mass spectrometry can be used to determine not only the consumption itself but also the type and frequency.

How long exactly THC can be detected depends on various factors:

  • Amount and frequency of consumption
  • The period between THC consumption and drug test
  • Type of drug test: blood test, urine test, or hair sample
  • the general condition of the individual

How long is THC detectable in the blood?

Depending on the frequency of consumption and the amount of active ingredient ingested, the THC detectability in the blood plasma is about four to six hours. After smoking a low-dose cannabis cigarette, THC is no longer detectable after about 7.2 hours. With a high-dose cannabis cigarette, the limit of detection is reached after about 12.5 hours.

However, the metabolite THC carboxylic acid can be detected in the blood plasma over a much longer period. With a single consumption, the THC detectability is about one to three days. If consumed several times, residues of THC carboxylic acid can be found in the blood plasma three to seven days after the last THC intake. With regular consumption, the blood test can still be positive several weeks after the last THC intake.

In summary: Depending on the consumption pattern, active THC can be detected in the blood approximately 12 to 72 hours after consumption, while THC metabolites can still be detected for up to several weeks.

How long is THC detectable in urine?

The urine test is the most commonly used method for detecting THC because THC can be detected in urine much longer than in blood, for example. The degradation product THC-carboxylic acid can still be detected in the urine after 24 to 36 hours, even if it is only consumed once.

In the case of repeated consumption, the detection period is about five to seven days. If cannabis is consumed regularly, this can still be found with a urine test after six to eight weeks. With continuous consumption, THC can even be detected for up to 12 weeks.

How long is THC detectable in hair?

Another method for detecting THC is hair analysis. The degradation products of THC are incorporated into the hair matrix during hair growth. They can be detected for a long time. On average, hair grows about one centimeter per month. A THC uptake that took place a year ago could be determined in twelve-centimeter long hair.

However, the hair test for THC is very error-prone and inaccurate. On the one hand, even regular consumption is often not recognized. On the other hand, false-positive results can occur, for example, when using a hair shampoo that contains ingredients similar to THC.

In forensic medicine, blood and urine testing is used to detect THC.

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