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Drug Tests 101 – What Everyone Should Know About Screening

Drug-Testing Guide

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A drug test, sometimes also referred to as drug screening, is any test administered for the technical analysis of biological specimen of human body (such as blood, urine, saliva, hair, sweat etc.), in order to detect the presence, or in some cases any prior use, of illicit parent drugs or their metabolites. A metabolite is basically the inactive metabolized form of a parent drug.
The drugs someone did last night, at the weekend party, or even on last New Year’s eve – they can all be in the system, be it blood, urine, saliva, or even hair, waiting to be detected either by the government, employer, or parents when they use drug testing kits for home use.

Table of Contents

Drug Tests Uses

Drug tests are used to detect the use of illicit drugs in job applicants, athletes, criminal offenders, participants of drug rehabilitation programs, and others. If illicit drugs are detected, the person usually endures some sort of consequence.
Knowledge is power. The more one learns about drug tests, the better their chances are to get prepared to it, so let’s get started.
Only a few decades ago, the human body was shielded from the outside world just like a well-built fortress, and detecting what’s inside it was nearly impossible. Fortunately, recent advances in science have given birth to sophisticated drug testing.

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Types of Drug Tests

There is a wide variety of drug tests which can be divided into two major categories: doing drug testing at home and professional drug testing done by a qualified expert, usually in a sophisticated facility.

At Home

Several drug tests, such as urine test or saliva/oral fluid tests can be easily done at home. All one needs to do is buy one of the home drug test kits available as over-the-counter strips, collect a sample of urine or saliva, dip the strip in the urine/saliva for the specified amount of time, and view the reading. These strips are available online as well as in stores, are fairly easy to use, and come with detailed directions. However, results from cheap drug test kits can usually be misleading and incorrect. Even if a person uses a high-quality kit, there are several external factors that can impact the results of the test, unless they do a lot of research, have some working knowledge of testing, and are very careful in their approach.

Are home drug testing kits accurate?

Home drug testing kits can provide accurate results if they are done very carefully. However, home drug testing kits, especially cheap ones, have the potential to be misleading or inaccurate considering there are a number of external factors that can affect the test’s results that someone doing the test at home may not know about.


Professionally conducted drug tests are more accurate, offer a deeper insight, and are more expensive. There are different types of professional drug tests including urinalysis (urine test), swab (saliva test), blood test, hair follicle test and so on.


To realize the popularity of the urinalysis, consider this fact: 90% of the 55 million drug tests performed last year were urine tests. Because the majority of the drug is already metabolized, the urine test, instead of detecting illicit parent drugs, tries to detect the presence of non-psychoactive drug metabolites. For example, marijuana’s primary metabolite is THC-COOH which is fat soluble and can be detected in urine for up to two weeks. Urine testing, despite its popularity, is believed to be the easiest of all tests to beat.

Any attempt to cheat on the drug test is a violation of the law. Do not attempt to falsify the drug test results to avoid the negative consequences. Note that there is no foolproof way to have a clean drug test result, except for abstaining from drug use.

Blood Test

A blood test is the most invasive and the most accurate form of drug testing. Unlike the urine test, a blood test actually detects the presence of parent drugs and not their metabolites because most substances, such as nicotine and marijuana, are quickly absorbed by the bloodstream and are easily detectable. Since blood tests are the most expensive type of tests, they are less common and are only administered if a lot of money or the law is in question. It should be noted that most drugs do not stay in bloodstream for too long. For example, marijuana generally becomes undetectable by blood tests after a few hours of use, but in chronic users it can stay detectable for more than 24 hours.


Saliva testing for drugs is administered to detect the presence of parent drugs. It’s less invasive than the urine test and less expensive than the blood test, however it’s accuracy can be questionable if not done right. For instance, very small amounts of THC from marijuana, or nicotine from tobacco, are released into the saliva. Therefore the detection window for drugs via a saliva test is very small – generally just a few hours after use. However, some drugs enter oral fluid through diffusion from the bloodstream and can be detectable for longer periods. The ease of use and low cost are the key factors which makes the saliva test a popular testing method.

Hair Follicle

Commonly used by labs and for research purposes, hair follicle testing is very hard to beat but can be the least accurate approach for several reasons. The test tries to detect the presence of drug metabolites diffused from the bloodstream into the follicle. The hair test can offer data like no other test can, including not only the presence of drugs but the patterns of drug use. For example, if someone used a drug, then abstained for a certain amount of time, and then used it again, the hair follicle test will reveal this data.
With the hair follicle test, contamination from the subject’s surroundings is a major issue. Even the smallest amount of a powder or smoke can attach to the hair, and could result in a false-positive test result. While some renowned laboratories try to dismiss this claim, many experts believe that dark hair acts as a stronger magnet for contaminants compared to white hair, making people with dark hair more prone to false-positive results.

What is the most common type of drug test?

The most common type of drug test is the urine test, or urinalysis. Of the 55 million drug tests which were administered in 2015, 90 percent of them were urine analyses. A urine analysis is much cheaper than other tests and tends to have a longer detection time compared to tests conducted with blood or saliva samples.

Accuracy and Reliability of Drug Tests

Drug testing can be accurate if done properly, but the results can be extremely misleading. The accuracy depends largely on the standards for sample collection, whether the collection was performed inside the detection window of the drug, and whether it was a random drug test or the subject had prior knowledge of the testing.
The accuracy of drug testing results depends on how strictly the specimen was collected. For instance, when urine is collected, its temperature should be between 96 and 99 degrees. Otherwise, the subject might have contaminated their urine and the results may be inaccurate.
It’s important to remember that drugs can have different detection window depending on the test. Specimen collected too soon or too late will not provide accurate results. For example, most drugs can appear in blood stream very quickly but also leave the system shortly after the use. Likewise, oral fluid testing is most accurate when administered immediately after drug use. On the other hand, the same substances will take some time to be metabolized in the body and appear in the urine test.
The random drug testing of subjects or not giving them knowledge of the test in advance generally does not give the subject the opportunity to abstain from using drugs and producing a negative result on the drug test.

Applications of Drug Testing

What are the major applications of drug testing? Drug testing is on a decline in the United States, because an increasing number of employers believe that there is little benefit for the required cost and hassle. The government as well as drug-test industry have insisted for years that proper drug screening will ensure safety and enhance productivity. However, the rate of drug testing has dropped from 81% in 1996 to 62% in 2004. The most prolific drug tester in the United States is the federal government, subjecting 400,000 employees to drug tests. However, there are several other scenarios where drug tests may be administered:

  • Drug testing by employers to detect the use of illicit drugs
  • Screening of athletes and sportsmen to detect any illicit performance enhancing drugs
  • Drug testing by the police, for instance to identify whether a subject had illicit substances in their body after an accident or a DUI citation
  • Insurance companies performing a drug test before they allow an individual purchase an insurance plan
  • Testing as a result of court order, usually in cases of child custody, after allegations of drug abuse or date rape
  • Testing by a health professional to identify the cause of a disease an individual is suffering from
  • Drug testing to monitor a person who is abstinent or has joined a drug abuse prevention program
  • Screening before an individual undergoes orthopedic surgery, plastic surgery, a spinal fusion, a wound revision, an organ transplant, or pulmonary therapy
  1. Fretthold D. W. Drug-testing methods and reliability. 1990; 22(4): 419-28.
  2. National Institute of Justice. Improving the Reliability of Drug Tests Done by Officers. 2016.
  3. The US Food and Drug Administration. Drugs of Abuse Home Use Test. 2018.
  4. National Institute on Drug Abuse. Drug Testing. 2017.
  5. Medline Plus. Drug Testing. 2017.


Leave a comment

  • Deana
    A failed positive how likely is that when I know I’m not doing phetnyl
    • Wads
      Do you take suboxone? I just tested positive for oxy. Upon research I learned naloxone can cause false results I take no other drug! Except subs
    • Crystal
      If there’s not 15 cc of urine, can you have a false positive?
    • Amanda
      So i was screened at my dr app and it showed negative for all the meds I take. I insisted it was wrong so they sent it off to a lab well guess what results showed i take all my meds! Dr said she ordered wrong test and thats why results were wrong? How can that be?
  • Heather
    I had a test say I had Suboxone in my system.and I was pregnant I demanded it be re tested because the paper said the keep urine for around 30 days…read your paperwork because I knew I didn’t put anything into my.body and here it was a cross contamination whatever that meant…it was a lab mistake.
  • JaJaBinks
    Did random urine drug test at pain management clinic and my test came out positive for a drug called fentanyl even though I didn’t take any of that sort. My doctor knows I sometimes use marijuana for my chronic pain and suggested that maybe the one I used may have been laced with that drug….very scary. We did another test to make sure it wasn’t just a false positive so just waiting now. My question now is will that second test be able to identify if it did in fact came from the marijuana I used?? I’ve also been trying herbal stuff I got online so not sure if that’s the culprit too.
    • Jay618
      I dont know about your test question but i live in Baltimore and ppl are putting fentanyl in everything on the street from weed to pills to cocaine not just heroin like mant ppl think dumb mfers are putting it in everything i guess hoping ppl will get hooked and buy more im so happy China is passing laws to ban fentanyl production
  • Sarah A Eisen
    i am curious about the metabolite cutoffs, I am prescribed xanax 2 mg daily as needed. I took a drug test the following morning and I am pretty sure I had taken 2 mg the night beofr as I was upset (another story). My level on my test is 413 for Alphahydroxyalprazolam (the metabolite of xanax) it’s all I take so I am just wondering if that is normal?
  • Laurie
    I have to see PO on Monday It’s Sat and I have had 4 shots of Tequila. Plus drank 3 beers Friday night. Been drinking tons of water Will I pass Drug test?
    • Vortec
      probably. cool it on the water though, as it will more than likely dilute your urine and make your results inconclusive. In the eyes of the law, that means you attempted to circumvent the test and they might fail you.
  • Shop
    What about I have a drug screening in less than a week for epiditimitis in my testicle ,it had trace of blood before ,the concern is my gall bladder as well,point is ,the doctor won’t remove my testicle or look into my Go adder if I have any amphetemines or stimulants in my many days do I have to flush these metalobites out and still get an accurate blood count .
  • Christy Shaddix
    Question: can you pass a hair drug test yet at same time fail urine drug test?
    • Vortec
      depends on whether its a lab test or at home test. too msny variables. your question is too broad.
  • Linda
    I have been on morphine sulfate time release 60 mg a twice a day and morphine sulfate 30 mg 4 times a day break through for almost 14 years I recently took a drug screen at my new pain doctor and it came back positive for 16 in MA not 16 scuse me came back for 6 p.m. a.m. he told me that it was positive for heroin that that’s what that meant I’ve never take heroin or street drugs in my life ever I’m 64 years old why would that come back like that I’m told that morphine can come back a false positive sometimes but I’ve never had this happen can you please explain to me why this test has come back positive and this past Friday I had my family doctor retest me I had a blood test and urine tests done I want to get my name cleared I am been so very upset over this thank you for your
  • Chris Zimmerly
    What year did the DOT regulation come out to start pre-employment drug testing?
  • Denise
    I would like to know where I can get and see the actual results from my drug screen. I need to see it for myself.
    • David
      You have EVERY right to view the results
  • christine mumaw
    my husband goes to pain managment for broken neck and back and every drug test they took on him keeps coming back neg why we dont understand it why it keeps coming back neg although he is a diabetic and drinks like 3 gallons of water a day and other fluids like tea and soda could that be the reason he is coming back neg all the time pluss he has keyoacidoses his A1c is high sugar never under 300
  • Keisha
    Yesterday I took a drug test for pre employment & when I gave the lady the urine sample she asked me did I take any medication & she was sticking the stripes in it.. I told her no & then she told me I can get my belongings out the cabinet & I left.. why would she ask me that? Do they just ask random questions like that
    • Nana
      They need to know if you’re taking any medication because if your test comes up positive for anything and your prescribed it then you’re fine.. also certain medications can cause false positives and they will have to do more extensive testing if that’s the case
  • Debbie Wooddell
    I took a drug test at my Drs. because I take hydrocodone and the law requires I take them at periodically. My drug tests have always been good. Then two test in a row showed no sign of the hydrocodone In my system. I take several different prescriptions. I started taking a new one, phentermine. Some of the other prescriptions I take are Omeprazole, Xanax, flexeril, gabapentin etc.. Is there any one or combination of prescriptions that can cause a false negative result for hydrocodone? I had taken 2 300/7.25 the day before my drug test. I don’t take them if I don’t need them on a day to day basis.
  • Lm
    Can breathing in a small amount of second hand smoke from heroin cause Urine test taken a few hours later cause a positive result for opiates even thought they haven’t used any opiates ?
  • Chad
    Soooo cool! I woke up and later in the day I started thinking about this stuff. I found your site on Google and it totally answered my questions. Thanks so much!
  • Danette
    I wiegh about 190lbs. Have notsmoked in 20 dayswhat are my chances of passing a urine drugh test withvthe help of niance
  • Bidu USA
    I will be doing a hair test for a new job, the test is 5DSP/EXP OPI hair (811). I am prescribed Adderall 10mg 2x day, sometimes based on workload I may take 3, but weekends and when I’m off I do not take it. I know that on the drug test it will show Amphetamines, but I am prescribed and have a valid prescription. My question would be on the dosage, my doctor is aware of me taking 3 sometimes and he is ok with it, but will the hair test show that sometimes I take 3? In another words, will they say that I am prescribed 20mg daily, but they found more? Not sure if they see the quantity or just whether the drug is in the hair. Thank you in advance.
  • Elroy24
    For work I tested urine(6061ng/ml) and oral (21ng/ml cocaine and 102ng/ml BZE…i got fired cause they think i was high at work but didn’t use for 15hrs..? I use daily and drink and smoke..i have thalysemia and wondering if I have metabolizing issues that could back my case up? Please and thanks
  • Jesse Ford
    Thanks for mentioning that drug tests are for detecting illicit drugs in job applicants, athletes, and others. My brother is thinking about getting a meth testing kit next week because he’s contemplating testing the workers he manages at his job. I think it’s a good investment to get a kit from a reputable company that will be able to let him know the results in a timely manner.