Sources of False Positive Results
All point-of-care (POC) test results are considered presumptive until they have been confirmed using liquid chromatography–mass spectrometry (LC-MS/MS). An in-office POC test provides a preliminary assessment of a patient’s medication compliance, but POC testing has generally accepted limitations. For example, POC testing has higher cutoff values than laboratory testing and POC test results apply only to drug classes, not to individual drugs. These limitations can lead to false negative or false positive test results, depending on what substances the patient has consumed. Therefore, it is important to obtain a full medication history that includes prescription, OTC and herbal medications for each collection event.
This chart is not inclusive of all substances with the potential to cause false positive test results. This chart is for general information only and is not intended to be used as medical advice. For specific drug testing result interpretation questions, please contact us.
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DRUG CLASS
DRUGS TARGETED BY THE POC TEST
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES
Amphetamines
Amphetamine
Amantadine, Brompheniramine, Bupropion, Chlorpheniramine, Chlorpromazine, Desipramine, Desoxyephedrine, Ephedrine, Fluoxetine, Isometheptene, Isoxsurpine, Labetalol, Phenmetrazine, Phentermine, Phenylephrine, Phenylpropanolamine, Promethazine, Pseudoephedrine, Ranitidine, Selegiline, Thioridazine, Tranylcypromine, Trazodone, Trimethobenzamide, Trimipramine, Vicks Inhaler
Methamphetamine
Amantadine, Brompheniramine, Bupropion, Chlorpromazine, Desipramine, Desoxyephedrine, Ephedrine, Fluoxetine, Isometheptene, Isoxsuprine, Labetalol, Phentermine, Phenylephrine, Phenylpropanolamine, Promethazine, Pseudoephedrine, Ranitidine, Selegiline, Thioridazine, Trazodone, Trimethobenzamide, Trimipramine, Vicks Inhaler
Antidepressants (Tricyclic)
Amitriptyline, Desipramine, Doxepin, Imipramine, Nortriptyline, other Tricyclics
Carbamazepine, Cyclobenzaprine, Cyproheptadine, Diphenhydromine, Hydroxyzine, Quetiapine
Barbiturates
Amobarbital, Butalbital, Phenobarbital, Secobarbital, other Barbiturates
Ibuprofen, Naproxen
Benzodiazepines
Alprazolam, Nordiazepam, Oxazepam, Temazepam, other Benzodiazepines
Oxaprozin, Sertraline, Hydroxyzine, Diphenhydramine
Opiates and Opioids
Codeine, Hydrocodone, Hydromorphone, Morphine
Dextromethorphan, Diphenhydramine, Fluoroquinolones (Ciprofloxacin, Levofloxacin, and Ofloxacin), Oxycodone (high contentrations), Poppy Seeds and Oil, Rifampin, Quinine
Methadone
Chlorpromazine, Clomipramine, Diphenhydromine, Doxylamine, Ibuprofen, Quetiapine, Thioridazine, Verapamil
Oxycodone, Oxymorphone
Codeine, Hydrocodone, Hydromorphone (high concentrations), Morphine
Illicits
Cocaine
Amoxicillin, Coca Leaf Teas, Tonic Water
MDMA (Ecstasy)
Phenylpropanolamine, Ephedrine, Pseudoephedrine, Ranitidine, Phentermine
PCP (Phencyclidine)
Chlorpromazine, Dextroamphetamine, Dextromethorphan, Diphenhydramine, Doxylamine, Ibuprofen, Imipramine, Ketamine, Lamotrigine, Meperidine, Thioridazine, Tramadol, Venlafaxine
Marijuana
Dronabinol, Efavirenz, Hemp-containing Foods, Ibuprofen, Ketoprofen, Naproxen, NSAIDs, Piroxicam, Prilosec, Promethazine, Proton Pump Inhibitors (Pantoprazole), Protonix, Sulindac, Tolmetin
DRUG CLASS
DRUGS TARGETED BY THE POC TEST: Amphetamine
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Amantadine, Brompheniramine, Bupropion, Chlorpheniramine, Chlorpromazine, Desipramine, Desoxyephedrine, Ephedrine, Fluoxetine, Isometheptene, Isoxsurpine, Labetalol, Phenmetrazine, Phentermine, Phenylephrine, Phenylpropanolamine, Promethazine, Pseudoephedrine, Ranitidine, Selegiline, Thioridazine, Tranylcypromine, Trazodone, Trimethobenzamide, Trimipramine, Vicks Inhaler
DRUGS TARGETED BY THE POC TEST: Methamphetamine
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Amantadine, Brompheniramine, Bupropion, Chlorpromazine, Desipramine, Desoxyephedrine, Ephedrine, Fluoxetine, Isometheptene, Isoxsuprine, Labetalol, Phentermine, Phenylephrine, Phenylpropanolamine, Promethazine, Pseudoephedrine, Ranitidine, Selegiline, Thioridazine, Trazodone, Trimethobenzamide, Trimipramine, Vicks Inhaler
DRUGS TARGETED BY THE POC TEST: Amitriptyline, Desipramine, Doxepin, Imipramine, Nortriptyline, other Tricyclics
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Carbamazepine, Cyclobenzaprine, Cyproheptadine, Diphenhydromine, Hydroxyzine, Quetiapine
DRUGS TARGETED BY THE POC TEST: Amobarbital, Butalbital, Phenobarbital, Secobarbital, other Barbiturates
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Ibuprofen, Naproxen
DRUGS TARGETED BY THE POC TEST: Alprazolam, Nordiazepam, Oxazepam, Temazepam, other Benzodiazepines
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Oxaprozin, Sertraline, Hydroxyzine, Diphenhydramine
DRUGS TARGETED BY THE POC TEST: Codeine, Hydrocodone, Hydromorphone, Morphine
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Dextromethorphan, Diphenhydramine, Fluoroquinolones (Ciprofloxacin, Levofloxacin, and Ofloxacin), Oxycodone (high contentrations), Poppy Seeds and Oil, Rifampin, Quinine
DRUGS TARGETED BY THE POC TEST: Methadone
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Chlorpromazine, Clomipramine, Diphenhydromine, Doxylamine, Ibuprofen, Quetiapine, Thioridazine, Verapamil
DRUGS TARGETED BY THE POC TEST: Oxycodone, Oxymorphone
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Codeine, Hydrocodone, Hydromorphone (high concentrations), Morphine
DRUGS TARGETED BY THE POC TEST: Cocaine
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Amoxicillin, Coca Leaf Teas, Tonic Water
DRUGS TARGETED BY THE POC TEST: MDMA (Ecstasy)
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Phenylpropanolamine, Ephedrine, Pseudoephedrine, Ranitidine, Phentermine
DRUGS TARGETED BY THE POC TEST: PCP (Phencyclidine)
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Chlorpromazine, Dextroamphetamine, Dextromethorphan, Diphenhydramine, Doxylamine, Ibuprofen, Imipramine, Ketamine, Lamotrigine, Meperidine, Thioridazine, Tramadol, Venlafaxine
DRUGS TARGETED BY THE POC TEST: Marijuana
SUBSTANCES WITH POTENTIAL TO CAUSE FALSE POSITIVES: Dronabinol, Efavirenz, Hemp-containing Foods, Ibuprofen, Ketoprofen, Naproxen, NSAIDs, Piroxicam, Prilosec, Promethazine, Proton Pump Inhibitors (Pantoprazole), Protonix, Sulindac, Tolmetin
The information provided is for educational purposes only and is not intended to be used as medical or legal advice. Detection times are approximate and may be influenced by a number of factors, including BMI, duration of drug use, dosage and interindividual metabolic differences. For specific drug testing result interpretation questions, please contact us.