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False Positives

What Can Cause a False Positive On a Drug Test?

False Positives – 2024 Updates

In 2024, drug testing continues to be an essential aspect of various sectors, from healthcare to employment. However, there are a few factors that can cause the occasional false positive on immunoassay drug tests. Such results can create unnecessary stress and complications, especially for individuals who haven’t consumed any illegal drugs. This article aims to explain the causes of false positives in drug tests, and what this means for employers and individuals alike. We’ll also provide insights into the common substances that might trigger these unexpected outcomes.

false positives

 

The year 2024 marks a significant evolution in the field of drug testing. With advances in technology, drug tests have become more sensitive, yet the risk of false positives persists. This is largely due to the increased complexity of substances being tested and the variety of legal medications and foods that can interfere with test results. For instance, the development of new synthetic drugs and modifications to existing ones can challenge the accuracy of traditional testing methods.

Implications for Employers in 2024

For employers, navigating the landscape of drug testing in 2024 requires careful consideration. With the possibility of false positives, companies must ensure their drug testing policies are robust yet fair. In some cases, implementing confirmatory testing, such as Gas Chromatography-Mass Spectrometry (GC-MS), can help verify initial results and reduce the incidence of false positives.

Challenges of Pre-employment Screening

Pre-employment screenings have become standard practice for many organizations. These tests are designed to ensure that potential hires are free from substances that could impair their job performance. However, the possibility of a false positive on a drug test poses a challenge for both employers and job seekers.

For those who are taking prescription drugs regularly, it is important to be aware of the type of medication they are consuming and how this may affect their drug test results. In fact, some have tested positive for drugs on the employment screening that they have never taken.  How is this possible?  The consumption of certain over-the-counter medications, prescription medication, or specific food items may cause someone to test positive for drugs not taken. This is known as a false positive.

Candidates should be informed about the possibility of false positives and encouraged to disclose any medications or dietary habits that could affect their test results. Navigating these challenges requires a balance between maintaining workplace safety and respecting the privacy and rights of prospective employees. Clear communication and fair practices are essential in achieving this balance.

Causes of False Positives in Urine Tests

A false positive is a test result that incorrectly indicates a positive result of a particular substance. “False positives can happen when a test detects a substance that isn’t actually there,” said Georgina Rubal-Peace, PharmD, director of Medication Use Policy at Banner Health in Tucson, AZ. “These imposter substances can be byproducts of prescription or over-the-counter medicines, nutritional supplements, and sometimes in certain foods. They may not be illegal, but they inaccurately appear as such.” Understanding these causes of a false positive can help individuals and employers better prepare for and interpret test results.

False Positives

Alcohol (EtG)

Substances That Can Cause A False Positive For EtG:

  1. Heavy use of hand sanitizer that contains alcohol
  2. Certain liquid medications including Nyquil and similar cold medications
  3. Kombucha
  4. Large amounts of apple juice
  5. Mouthwash or other breath cleansing products

 

Amphetamines (AMP)

Substances That Can Cause A False Positive For AMP:

  1. Amantadine
  2. Brompheniramine
  3. Bupropion (This is used as an antidepressant and smoking cessation aid, also structurally similar to amphetamine)
  4. Chlorpromazine
  5. Dextromethropan
  6. Diphenhydramine
  7. Doxylamine
  8. Naproxen
  9. Promethazine
  10. Quetiapine
  11. Quinolones (ofloxacin and gatifloxacin)
  12. Ranitidine
  13. Sertraline
  14. Thioridazine
  15. Trazodone
  16. Venlafaxine
  17. Verapamil
  18. Dexamphetamine Sulphate
  19. Pseudoephedrine and Phenylephrine (popular decongestants that share similar structural characteristics with amphetamines)
  20. Phentermine
  21. Beta blockers like labetalol (Trandate)
  22. Diet pills like phentermine (Adipex-P)
  23. Medication to treat nausea and vomiting like phenothiazines (Promethazine)
  24. Over-the-counter cold, sinus, and nasal decongestants like ephedrine and pseudoephedrine (Sudafed) and Vicks inhaler
  25. DMAA, an ingredient in some dietary and weight-loss supplements including Oxyelite Pro.
  26. ADHD (attention deficit hyperactivity disorder) medications like methylphenidate (Ritalin)
  27. Antidepressants like bupropion (Wellbutrin), fluoxetine (Prozac) and trazadone (Desyrel)

Substances That Can Cause A False Negative For AMP:

  1. MDMA (ecstasy)
  2. Synthetic amphetamines (cathinones, bath salts, etc)

 

Barbiturates (BAR)

Substances That Can Cause A False Positive For BAR:

  1. Ibuprofen (Motrin, Advil)
  2. Naproxen (Aleve)
  3. Allobarbital
  4. Alphenol
  5. Amobarbital
  6. Aprobarbital
  7. Butethal
  8. Butalbital
  9. Butisol
  10. Soneryl
  11. Nembutal
  12. Donnatal
  13. Luminal
  14. Phenytoin
  15. Seconal
  16. NSAIDs
  17. Sleep aids like doxylamine (Unisom)

 

Benzodiazepine (BZO)

Substances That Can Cause A False Positive For BZO:

  1. Sertraline
  2. Oxaprozin (Daypro)
  3. Efavirenz
  4. Naproxen and oxaprozin
  5. Alprazolam ( Xanax)
  6. Bromazepam
  7. Tranxene
  8. Librium
  9. Frisium
  10. Briantum
  11. Diazepam
  12. ProSom
  13. Rohypnol
  14. Paxipam
  15. Pacinone
  16. Lorazepam
  17. Noctamide
  18. Nitrazepam
  19. Serax
  20. Restoril
  21. Ibuprofen
  22. Selective serotonin reuptake inhibitors (SSRIs) like sertraline (Zoloft), which can be used to treat depression, post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), social anxiety disorder and panic attacks.

 

false positives

 

Buprenorphine (BUP)

Substances That Can Cause A False Positive For BUP:

  1. Morphine (Medical practitioners should be aware that high-dose morphine – with morphine urine levels turning positive within the 15,000 to 28,000 mg/mL range – may produce false-positive buprenorphine EIAs with standard urine EIA toxicology testing.)
  2. Methadone
  3. Codeine
  4. Dihydrocodeine

 

Cocaine (COC)

Substances That Can Cause A False Positive For COC:

  1. Coca Tea (Coca tea is made from the leaves of the coca plant, also the source of cocaine)
  2. Lidocaine
  3. Fluconazole
  4. Zolpidem
  5. Being exposed to someone actively using cocaine or disposing of someone else’s cocaine

 

Cotinine (COT)

Substances That Can Cause A False Positive For COT:

  1. Nicotine

 

Fentanyl (FEN)

Substances That Can Cause A False Positive For FEN:

  1. MDMA
  2. Vyvanse
  3. Ziprasidone
  4. Diphenhydramine
  5. Poppy Seeds
  6. Codeine
  7. Methamphetamine
  8. Trazodone
  9. Risperidone and its metabolite 9-hydroxyrisperidone share an intramolecular alkylated piperidine acetyl fentanyl
  10. Loperamide
  11. Doxylamine
  12. Quinolone antibiotics
  13. Rifampin
  14. Ciprofloxacin
  15. Moxifloxacin
  16. Norfloxacin

 

Ketamine (KET)

Substances That Can Cause A False Positive For KET:

  1. Quetiapine
  2. Promethazine

 

Kratom (KRA)

Substances That Can Cause A False Positive For KRA:

  1. Methadone Metabolite (EDDP)

 

Methadone (MTD)

Substances That Can Cause A False Positive For MTD:

  1. Benadryl
  2. Verpamil
  3. Quetiapine
  4. Benadryl
  5. Medinex
  6. Nytol
  7. Panadol Night
  8. NyQuil
  9. Dolophine
  10. Physeptone
  11. Tylenol PM
  12. Advil PM
  13. Diphenhydramine
  14. Doxylamine
  15. Clomipramine
  16. Chlorpromazine
  17. Quetiapine
  18. Thioridazine
  19. Tonic water contains quinine, and when consumed in large amounts, could lead to false positive results for opiates.
  20. Poppy Seeds: Consuming poppy seeds before a drug test (such as in a muffin or on a bagel) could cause a false positive drug result for opioids. Poppy seeds come from the seedpod of the opium poppy, and while the seeds are cleaned before consumption, they may still contain trace amounts of opium residue. In 1998, the federal government raised the threshold on opiates from 0.3 micrograms to 2 micrograms per milliliter, but some testing facilities still go by the old standard.

 

THC

Substances That Can Cause False Positive Test Results for THC:

  1. Naproxen
  2. Ibuprofen
  3. Baby washes
  4. Hemp food products
  5. HIV medication like efavirenz (Sustiva)
  6. Proton-pump inhibitors, specifically pantoprazole (Protonix)
  7. Some vitamin B supplements that come from hemp seed oil
  8. Promethazine
  9. Riboflavin
  10. Ethacrynic acid
  11. Cannabidiol (CBD) oil

Urine drug tests screen for the presence of THC, the psychoactive component of marijuana, but a problem could arise because these products are not very well-regulated, and cross-contamination can occur. “With CBD available in everything from drink powders, to weight loss formulations, to tinctures of all types, false positive urine tests for THC will become more and more common,” warns Dr. McFadden.

Hemp is any part of a cannabis plant that contains 0.3% THC or less. CBD products made from hemp could have small amounts of THC in them even if it is not listed on the label. This means that people who use CBD regularly could build up high enough THC levels in their bodies to test positive.

Substances That Can Cause False Negative Test Results for THC:

  1. Synthetic Cannabinoids

 

Marijuana

Does passive smoke inhalation cause a false positive for marijuana? It is possible to receive positive test results for marijuana due to passive smoke inhalation.  Consider a few scenarios: 

  • Residing in a small, poorly ventilated room or an enclosed vehicle with other active marijuana users.  
  • The marijuana being smoked has very high levels of THC (the active ingredient in marijuana) – one stays for at least an hour in proximity with the marijuana users – one is tested immediately or up to a few hours after.
  • It is important to remember that urine tests have cut-off levels high enough to limit false-positive results. In other words, the cut-off levels would have to be very low to test positive for secondhand marijuana smoke exposure.

 

Methamphetamine (MET)

Substances That Can Cause A False Positive For MET:

  1. Decongestants
  2. Ritalin (methylphenidate)
  3. Adderall
  4. Quinolone antibiotics like Levofloxacin or Ofloxacin
  5. Metformin
  6. Desoxyn
  7. Methedrine
  8. Methamprex
  9. Vick’s Inhaler
  10. Pseudoephedrine
  11. Promethazine
  12. Trazodone
  13. Bupropion
  14. Brompheniramine
  15. Chlorpromazine
  16. Clomipramine
  17. Dextromethorphan
  18. Diphenhydramine
  19. Doxylamine
  20. Ibuprofen
  21. Naproxen
  22. Quetiapine
  23. Quinolones (ofloxacin and gatifloxacin)
  24. Ranitidine
  25. Sertraline
  26. Thioridazine
  27. Venlafaxine
  28. Verapamil

 

Opioids (OPI)

Substances That Can Cause False Positive Test Results for OPI:

  1. Verapamil
  2. Poppy Seeds or an “everything” bagel
  3. Benadryl
  4. Tylenol 3
  5. Tylenol with Codeine
  6. Codeine Phosphate
  7. Dihydrocodeine
  8. Ethylmorphine
  9. Vicodin
  10. Lorcet
  11. Dilaudid
  12. Hydrostat
  13. Kaolin and Morphine mixture
  14. Pholcodine
  15. Dextromethorphan
  16. Quetiapine
  17. Quinolone Antibiotics (Like levaquin and ofloxacin)
  18. Anti-psychotic medications like quetiapine (Seroquel)
  19. Benadryl
  20. Tylenol PM
  21. Advil PM, and other medications contain diphenhydramine

Substances That Can Cause False Negative Test Results for OPI:

  1. Fentanyl
  2. Hydrocodone
  3. Hydromorphone
  4. Meperidine
  5. Methadone
  6. Oxycodone

 

Oxycodone (OXY)

Substances That Can Cause A False Positive For OXY:

  1. Vicodin
  2. Lorcet
  3. Dilaudid
  4. Hydrostat

 

Ecstasy (MDMA)

Substances That Can Cause A False Positive For MDMA:

  1. Love Drug (MDA)
  2. Trazodone
  3. Metoprolol and the fenofibrate metabolite, fenofibric acid
  4. Bupropion
  5. Antipsychotic drugs such as promethazine and chlorpromazine

 

Phencyclidine (PCP)

Substances That Can Cause A False Positive For PCP:

  1. Dextromethorphan
  2. Ketamine
  3. Tramadol
  4. Venlafaxine
  5. Naproxen
  6. Ibuprofen
  7. NyQuil
  8. Imipramine
  9. Meperidine
  10. Doxylamine
  11. Lamotrigine
  12. Clonazepam
  13. Benadryl
  14. Tylenol PM
  15. Advil PM, and other medications contain diphenhydramine
  16. SNRIs, such as Effexor XR or Pristiq

 

Propoxyphene (PPX)

Substances That Can Cause A False Positive For PPX:

  1. Methadone
  2. Cyclobenzaprine (Flexeril)
  3. Doxylamine (Ny-Quil)
  4. Diphenhydramine (Benadryl)
  5. Imipramine

 

Tricyclic Antidepressants (TCA)

Substances That Can Cause A False Positive For TCA:

  1. Carbamazepine
  2. Cyclobenzaprine
  3. Diphenhydramine
  4. Phenothiazines
  5. Dextromethorphan
  6. Meperidine
  7. Doxylamine
  8. Ketamine
  9. Lamotrigine
  10. Tramadol
  11. Venlafaxine and desvenlafaxine
  12. Amitriptyline
  13. Flexeril
  14. Periactin
  15. Prothiaden
  16. Sinequan
  17. Xepin
  18. Gamanil
  19. Lomont
  20. Promethazine
  21. Certain antipsychotic medications
  22. Antihistamines

 

Tramadol (TRA)

Substances That Can Cause A False Positive For TRA:

  1. Venlafaxine
  2. Fexofenadine hydrochloride for treatment of skin allergies

 

Poppy Seeds

Why do poppy seeds cause a false positive drug test? Consuming any food item with poppy seeds before submitting a drug test can give a false-positive result. Poppy seeds come from the plant opium poppy. When the seeds are gathered, they may be coated with opium extract.  Opium extract, incidentally, is used in making drugs like morphine and heroin. Poppy seeds generally go through cleaning before being used in food. However, the seeds still contain small amounts of opium extract, which can lead to false-positive results.  It is best to avoid any products containing poppy at least three days before undergoing any urine drug testing.

Should I Stop Taking Medications or ‘Detox’ Before a Drug Test?

Don’t stop taking any medications without prior approval and guidance from your healthcare provider. As well, avoid any quick-fix remedies or detoxes that “make promises” to help you pass drug tests. Their clams don’t hold up — some can even be harmful. “Remedies purported as magic detoxes on social media, such as taking niacin before a drug test or goldenseal, an herb in the buttercup family, have not been shown to ‘trick’ a drug test and may cause liver injury in high doses” Dr. Rubal-Peace said.

How to Handle Your Drug Test

If you regularly use certain medications, supplements, or foods that could potentially trigger a false positive result, let whoever is performing the test know beforehand. Be prepared to bring or provide a list to the laboratory. Getting in front of the issue will protect you from a potential false positive.

  • Some cut-off levels might be very high and will not pick up minute traces.
  • If you suspect a false positive or negative result, please perform a separate test with just water as a control.
  • Double-check cross-reactions with any medications the patient might be taking.
  • A faint line on a drug test is considered a line

 

Moving Forward With Confidence

Understanding the potential for false positives is crucial for anyone conducting a drug test, whether you’re an employer, healthcare professional, or an individual. By remaining informed about the substances that can interfere with test results, you can take proactive steps to mitigate the risk of a false positive result. Individuals can benefit from maintaining a record of their medications and dietary habits to present in case of unexpected test results.

For those seeking further guidance, the team at 12 Panel Now is available to provide assistance. Staying informed, proactive, and transparent are the best strategies for managing the complexities of drug testing in today’s world.

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