How Long Does Marijuana Stay in Your System? Answering the Question

"How long marijuana stays in your system" is an interesting question,
and a very popular one on the Internet. Answering it is trickier than
you might believe, but the answer is important if you are
administering a drug test.

The first important distinction to make is that even if someone is no
longer experiencing the effects, or "high," of marijuana, it is still
in their system. And it is not so much marijuana that is in your
system, but its active chemical, THC (Tetrahydrocannabinol).

Drug tests look for THC by analyzing saliva, hair, or urine, and
sometimes blood. The variation in how long THC can be detected in a
standard saliva, hair, or urine consumer drug test might surprise you.

In the case of saliva, marijuana escapes the system quickly and takes
longer than most drugs to be detected. About an hour after use,
marijuana can be detected by a home saliva drug test. It takes about
12 hours for marijuana to begin leaving saliva - after that time, the
accuracy of a saliva-based home drug test drops greatly.

When it comes to urine drug testing, the amount and frequency of
marijuana smoked by the user makes a huge difference in how long THC
can be detected. Marijuana can stay in your urine for up to 45 days;
somewhere between a week and 30 days is more typical. Someone who uses
marijuana frequently or daily can expect to be positive on a drug test
for at least three weeks or more after giving up the habit. And
one-time users should not expect to get a negative drug test result
just because they only tried the drug once - a urine drug test will
still find them positive from a few days to over a week after use.
Marijuana use can generally be detected from 2-5 hours after initial
use in the urine.

Although marijuana/THC may have left the saliva and urine, it can
still stay in your system - in your hair follicles. When you consume a
drug, it enters the bloodstream. Blood nourishes your hair and helps
it to grow, and if the blood has any drug traces in it, they become
trapped in the hair and grow out along with it. After about a week of
drug use, the hair will grow out far enough from the scalp to be cut,
and drug use can be detected in that hair. Drugs take a very long time
to deteriorate in hair - consumer hair testing labs will only go back
90 days (industry standard) but courts and so forth can mandate a test
that analyzes the hair over a longer period. Naturally, your body hair
will also contain drug traces, and since body hair grows more slowly,
the detection window for body hair is considered to be a year. The
only caveat is that with hair drug testing, marijuana does not always
incorporate well with the hair, so even a frequent user may test
negative (while someone who smokes rarely might test positive). It is
unknown as of yet why this is the case, as this phenomenon does not
occur with any of the other commonly hair tested drugs like cocaine.
Basically, hair drug testing can detect marijuana in your system, but
is less reliable than urine tests, which are 98% accurate.

One of the factors that most influences how long marijuana stays in
your system is the frequency of use. THC is fat soluble, and when
marijuana is smoked the fat cells in the body absorb the THC. Over a
few days, the THC diffuses into the blood and your body becomes clean.
However, if you continually smoke, more THC will be taken into your
fat that can be let out into the blood, and thus THC (and therefore,
evidence of marijuana use) will stay in your system much longer. In
fact, the New Scientist, a scientific journal, documents (rare) cases
of former heavy users who, experiencing significant weight loss, start
excreting "old" previously stored THC into the blood as a result of so
much fat being burned up.

So when you ask the question of how long marijuana stays in your
system, it is important to note - what part of the system do you mean?
If you are testing a child or an employee you suspect of long-term
use, you will want to ask these questions. Since marijuana is so
variable, it may prove most wise to simply purchase a drug test and
find out if you or the person you want to test is indeed clean.

Robyn Schelenz is an author with Home Health Testing, an online home
health and home drug test business. You can learn more about marijuana
and drug testing by visiting our Marijuana Drug Test page.

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