How far does
it go back?
Hair testing generally uses 1-1/2 inches of hair,
representing about 3 months’ growth (head hair normally
grows at about 1/2 inch per month). It is generally
accepted that in order to test positive, the drug in
question must have been used 3 times or more within the
window of the test. After a drug is used, it takes about
7-10 days for the hair containing the drug to grow out
of the scalp enough to be cut. Therefore, the hair test
will not include drugs used in the week prior to the
test. The drug remains in the hair, growing out much the
same as hair dye and "dark roots". Eventually that hair
containing the drug is cut off with normal haircuts.
There are some prescriptions that contain the same drugs
that are commonly found "on the street". There is no
easy way to distinguish between the two forms of the
drug. However, the problem is not as big as it would
There are no prescriptions for PCP or cocaine. It is
extremely rare to find cocaine used in a medical
setting, although it happens occasionally, usually to
control bleeding from the eye or nose. If used, it will
be well documented in the person’s medical file. Such
use would cause the urine to test positive for cocaine
metabolite for a few days, but would not be sufficient
to cause a positive hair test.
Heroin is rarely prescribed in the United States, but
again would be well documented. It appears that poppy
seeds do not interfere in hair testing. Other prescribed
opiates may occasionally cause a positive screen, but
are sorted out in a confirmation test.
There are some prescription diet pills that contain
either amphetamine or methamphetamine, as well as a drug
for Parkinson’s Disease that is a form of
methamphetamine. Some doctors prescribe amphetamines for
ADHD. Ecstasy is included in the amphetamine class of
drugs, and is identified at confirmation.
What is "confirmation"?
Because there are substances that interfere with
screening, causing "false" positive results on
screening, the positive screen must be confirmed. The
accepted, state-of-the-art method is called GC/MS, gas
chromatography/mass spectrometry. Each drug peak comes
off the GC at a specific time (retention time), and with
specific ion ratios, allowing it to be separated or
distinguished from similar substances. To be called
positive, the peak in the sample must match a known pure
standard of the drug in question in both retention time
and ion ratios. In addition, the presence of metabolites
may be checked. For instance, amphetamine is the major
metabolite (what the body turns it into) of
methamphetamine. So, If there’s been methamphetamine
use, the hair should contain the methamphetamine AND
amphetamine. Likewise cocaine. Cocaine users will show
positive for cocaine AND the metabolite, benzoylecgonine.
Finding the parent drug without the metabolite for these
drugs is suspicious, and needs to be investigated.
What if I’m in a room with
someone who is using drugs?
Since it takes multiple uses to test positive, and
metabolites are checked when possible, it is pretty much
impossible to test positive from passive exposure on a
limited basis. Extreme passive exposure may result in
very low levels.
What if I bleach and/or dye my hair? Can I get rid
of the drugs?
No. The drugs are IN the hair, not ON it. Drugs are
actually incorporated into the hair shaft from the
bloodstream. Severe chemical washing and bleaching
removes drugs on the hair, and may, in some cases, lower
the level in the hair slightly, but it will not remove
the drug completely. As a matter of fact, before we do
our confirmatory testing, we wash the hair and test the
washes to make sure all the drug is off the outside of
the hair before we continue, so that we are assured that
any drug we find is from within the hair. Hair coloring
has no effect on the testing.
Where can I order an at
home hair drug test?
You can order one
though our online store.
Please note: If you are needing a hair test that is
court ordered or will be used for court please call us
at 800-989-1206 as you will have to go to a local clinic
to have the sample collected. Otherwise this test will
be consider an anonymous test as we cannot determine who
the hair belongs to when it is mailed in.
Order Instant Home Drug Testing Kit - Click Here