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Drug Tests: An Overview and Cautionary Measures

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Drug Tests: An Overview

Written by: Phillippe Greenough

Drug testing is ubiquitous in this day and age for all kinds of reasons. It is increasingly being used in the workplace and as a requirement for consideration for employment. Likewise, due to medical or mental health reasons tests are sometimes used to confirm compliance with prescribed medications. Of course, there are also legally required tests for those on probation, parole, or any other court mandated program. Finally, there are childcare related reasons for drug tests such as DFCS investigations and especially during pregnancy. Because of the myriad reasons for testing, and the unfortunate or possibly catastrophic consequences for failing a test, I have created this guide to help you avoid products or situations which may cause a false positive or a false negative result.  Of course, there are obvious things to avoid such as drugs, drinking alcohol, and using things containing alcohol which will legitimately cause you to fail such a test.

False Positive

A false positive is a result that shows a drug is present even if you have been abstinent. These are the most common type of drug test “malfunction” as there is a wide range of medications and chemicals which can interfere with a drug tests function. Likewise, some similar but distinct chemicals may produce metabolites which make it appear a drug has been taken when in fact it has not.

Results may also be affected by lab technician familiarity with the particular test being performed as well as the interpretation of the obtained results. Sometime it is always not a clear cut “yes or no” result, but will require a deep understanding of the drug being tested for, as well as the specific strengths and weaknesses of the test itself. The testing staff’s familiarity with these challenges will play a role in the outcome of a given test¹²³.

False Positives for Alcohol

There may be subtle causes for unexpected drug test failure from products which may contain alcohol, but do not have them listed in the ingredient list such as certain household or commercial cleaners. There are also many types of chemicals used in commercial or industrial sectors which may cause a false positive for alcohol. In particular, those who work in commercial painting, woodworking, or electronics repair need to be especially careful. Many of the solvents, paints, and laquers used in these fields can be absorbed through the skin and metabolites will end up in the blood or urine possibly resulting in a positive indicator for alcohol.

The FDA has this to say on the subject of home drug tests: If a result is positive, does that mean the person who tested was using drugs ? – “No. Take no serious actions until you get the laboratory’s result. Remember that many factors may cause a false positive result in the home test.”¹

False Positives for Methamphetamine

There are several common drugs which contain compounds which are enantiomers of illegal drugs but are used for different applications. One common example of an enantiomer drug is methamphetamine¹². The D isomer is what we know of as the illegal drug meth, while the L isomer is commonly used in many prescription and over the counter medications and does not produce the same neurological and physical effects. Most types of drug test do not differentiate between these isomers, and if you have L meth in your system it may give a positive result for meth. There are enantiomer specific tests, but these are expensive and are not done as a matter of course.

The FDA has this recommendation for any positive test results for meth/amphetamine: “Note that all amphetamine results should be considered carefully, even those from the laboratory. Some over-the-counter medications contain amphetamines that cannot be distinguished from illegally-abused amphetamines.”¹

Finally, there are many documented occurrences of confirmation tests creating a false positive for meth/amphetamines. There are newer tests which can be performed to elicit the exact structure of chemical compounds present in a urine sample, but these are very time consuming and expensive. Because of the similarity to amphetamines in structure and mass that many drugs exhibit, false positives for amphetamines remain some of the most common¹².

False Positive for Opiates

While opiates are used ubiquitously in legitimate medicine as painkillers, products containing trace amounts of opiates may be unknowingly bought at any grocery store. The poppy seed ***

False Negative

A false negative is when a test shows no drug presence when you have indeed been taking the drug. This can be caused by several factors. Typical urine tests have a certain threshold for detection, and if this threshold is not exceeded, they will read negative. Some of the causes for this can be:

  • Individual Metabolism: Some people have a faster metabolism than most, meaning that their body burns energy quicker. This can result in the drug getting filtered by the liver or kidneys quicker, producing lower than expected levels.
  • Time Between Drug Intake and Test: The longer a drug is in your body, the more your body is able to filter and excrete it in urine and sweat. If you test too long after taking the drug, the threshold may have been undershot. Likewise, it takes time for a drug to undergo first pass metabolism, so if you were to take a drug immediately before testing, it would not be present in urine for ~30 minutes to several hours depending on the drug.
  • Drug Interactions***

If you are certain you have taken the drug as required but receive a false negative, ask for the test to be sent off for analysis. Several more advanced types of test have a much greater specificity than quick urine tests and can be used to prove you have been compliant.

Types of Drug Tests

Since drug testing is so widespread, there have been many different types of tests developed. Urine immunoassay drug screens are some of the most common since they are cheap, easy to perform, and fast. Because of their simplicity, immunoassay tests are some of the worst offenders when it comes to false positives¹. These tests look for proteins that are produced by the body when certain drugs are present. Many harmless drugs have metabolites which will result in antigen or antibody production which make it appear like an illicit drug was used, and this is the source of most false positives in immunoassays¹.

Drug screen tests produced by different manufacturers will have slightly different interference profiles since the methods and detection thresholds may vary¹. Below is a small sample of different immunoassays and some known issues or benefits for each¹:

  • Syva EMIT II¹: Documented effectiveness with enantiomer differentiation between levo- and dextro- methamphetamine.
  • Roche KIMS¹:
  • Biosite Triage:
  • Agilent TesTcard9:
  • Abbott TDx/FLx:

There are several more sophisticated methods used for confirmation of an immunoassay tests findings, some of which include: gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), LC-tandem mass spectrometry (LC-MS-MS), and liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) *** ion something…

Cautionary Measures for Drug Testing

It should be common knowledge to avoid products containing drugs and alcohol if you are drug testing. We will not discuss the obvious culprits such as mouthwash¹², rubbing alcohol¹, hand sanitizer¹², *** as these should be apparent if you are considering carefully the products you use. There are more subtle culprits which may not be apparent at first glance. There are many items that you encounter in day to day life which may be dangerous to use if you are drug testing. Some common items may contain alcohol but do not have it listed on the ingredient list, so you must be vigilant and sometimes suspicious of the products you use. Likewise, many over the counter and prescription drugs may interfere with a test or produce metabolites which will give a positive result. Below are some known offenders in this regard:

Foods

  • Vanilla Extract¹: Ethyl Alcohol is a popular solvent used to extract the Vanilla flavor oils from the bean. Vanilla extract, either natural or artificial, contains at least 35% ethyl alcohol. When used in baked goods, baking evaporates most of the alcohol, but you can expect some to get into your system.
  • Cooking Alcohol (Brandy, Wine Vinegar, ): chicken picatta?
  • Anything Fermented: Kombucha
  • Chocolate Liquer: ?
  • Sugarfree Gum (Orbit ***): Sugar alcohol
  • Poppy Seeds: opiates

Cleaning Products

  • Odo-Ban¹: Ostensibly an ammonia based cleaner, it does indeed contain alcohol even though it is not on the ingredient list as an “active” ingredient.

Personal Hygiene Products

Because of the ability of alcohol to act as an effective solvent and disinfectant, it is common in many different types of personal hygiene products. Some are quite obvious while others are more elusive. Some common examples include:

  • Wet Wipes (Wet Ones¹): Many disposable hand or face wipes do contain alcohol. Baby wipes typically do not, but you should be safe and carefully read the ingredients before use.
  • Toothpaste (Crest+Scope):
  • Cologne or Perfume:
  • Astringents:

Automotive Products

  • Windshield Washer Fluid: contains methanol

Nutritional Supplements

  • Dimethylamylamine¹: A component of many pre-workout supplements and diet pills, it is known to produce false positives for amphetamine on both the Roche KIMS and Syva EMIT II tests. If a product says it contains “Geranium Extract” or “Geranium Oil” you should avoid it as it likely contains dimethylamylamine.

Medications

Many medications have documented and known interactions with drug testing procedures which may produce a false positive for a controlled substance¹. Some examples include drug classes which typically have no psychoactive effects at all, such as antibiotics and antihistamines. Some other frequent offenders do have psychoactive effects such as antidepressants, antipsychotics, analgesics, and a variety of nonprescription medications. The most important thing you can do is to notify the testing personnel of ANY medications you are taking; either over the counter or prescription. The following are just some of the more common and well studied false positive offenders, but there are many more.

Over the Counter Medications

Be sure to notify any testing personnel if you have taken any kind of medication whatsoever prior to testing. It would be in your best interest to give them a heads up for any possible false positives. Some frequent false positive offenders include:

  • Vicks VapoInhaler¹²³: Nasal decongestant inhaler whose active ingredient is L-Meth (Levmetamfetamin). May cause a positive result for Meth/Amphetamine.
  • Nyquil: contains alcohol
  • Naproxen (Aleve): A common NSAID pain reliever, it is known to produce false positives for // thc / barbiturates
  • Brompheniramine: ***
  • Dextromethorphan (Robitussin): opiates / pcp
  • Diphenhydramine (Benadryl): methadone / pcp
  • Doxylamine (Unisom): methadone / opiates / pcp
  • Pseudoephedrine (Sudafed): meth
  • Ranitidine (Zantac): meth
  • Ibuprofen (Advil): NSAID pain reliever which is extremely common. bar / thc / pcp
  • Loperamide???

Prescription Drugs

You should be sure to first notify the testing staff if you are on any prescription medications at the time of your test or in the recent past. There are known and documented interactions with urine tests from many non narcotic drugs which can nevertheless produce false positive results for narcotics. Some of these include:

  • Amantadine (Symmetrel)¹: An antiviral drug and also used to treat Parkinson’s disease as a dopamine agonist, it may produce false positives for amphetamine.
  • Amitriptyline: lsd
  • Brompheniramine (Dimetapp)¹: An antihistamine and cold medication, it is known to produce false positives for amphetamine, particularly with Syva EMIT tests.
  • Bupropion (Wellbutrin)¹²: This antidepressant and smoking cessation drug has documented false positives for meth/amphetamine or ecstasy (MDMA), particularly on the Syva EMIT II Plus test.
  • Buspirone: lsd
  • Chlorpromazine (Thorazine)¹: An antipsychotic medication, it is known to produce false positives for meth/amphetamine, particularly on the Syva EMIT-MAM and Agilent TesTcard 9 tests as well as false positives for PCP on the Syva EMIT II Plus test.
  • Clomipramine: ***
  • Desipramine (Norpramin)¹: An antidepressant and nerve pain analgesic, this drug is known to cause false positives for amphetamine.
  • Diltiazem: Used to treat hypertension and angina, / lsd
  • Fluoxetine (Prozac): meth / lsd
  • Gatifloxacin (Zymaxid)¹: A quinolone antibiotic used for eye infections, it is known to produce false positives for opiates on a variety of immunoassay tests.
  • Haloperidol (Haldol): An antipsychotic drug, it is known to produce false positives for ecstasy (MDMA), particularly on the Syva EMIT II Plus test.
  • Labetolol¹: meth/amph
  • Lamotrigine: pcp
  • Levofloxacin (Levaquin)¹: A broad spectrum antibiotic, it is known to produce false positives for opiates, particularly on the Syva EMIT II Plus test.
  • Metformin: A medication used to treat Type 2 Diabetes, it may produce false positives for meth/amphetamine.
  • Methylphenidate: meth / lsd
  • Metoclopramide: lsd
  • Ofloxacin (Floxin)¹: A broad spectrum antibiotic, it is known to produce false positives for opiates and meth/amphetamine, particularly on the Abbott TDx FLx (meth) and Syva EMIT II Plus (opiate) tests.
  • Prochlorperazine: lsd
  • Promethazine (Phenergan)¹: Antihistamine which can produce false positives for meth/amphetamine, particularly through the Syva EMIT II Plus and Agilent TesTcard 9 tests.
  • Quetiapine (Seroquel): methadone
  • Risperidone: lsd
  • Sertraline (Zoloft): benzo / lsd
  • Thioridazine: ***
  • Tramadol (Ultram): pcp
  • Trazodone (Desyrel)¹²: An antidepressant and sleep aid, it may produce false positives for both amphetamine or ecstasy (MDMA), particularly through the EMIT II (ecstasy) and the Roche Amphetamines II (amphetamine) tests.
  • Venlafaxine (Effexor): pcp
  • Verapamil (Verelan): lsd / methadone

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