If you have to get urine screenings for work, you may be concerned about teas or herbs that cause a false positive drug test. Well, there's bad news and good news. The bad news is that basic urine drug testing is highly inaccurate; the good news is that herbs are unlikely to raise a red flag.
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The other good news is that, if you do get a false positive on your initial screening, which is called an immunoassay, you can request a more in-depth urinary drug test, called a gas chromatography or mass spectrometry urinary screening. These tests are more expensive, but they're also more specific and have less cross-reactivity to herbs and beverages, minimizing the risk of a false positive.
Herbs, teas and beverages aren't likely to cause a false positive drug UA (or urinalysis) test, but other things, like poppy seeds, some over-the-counter medications and certain types of antibiotics, can trigger inaccurate results. If you do get a false positive, you can request more in-depth testing to show that illicit drugs were not the cause.
Types of UA Tests
There are two types of UA drug tests. The first — and more commonly used — is called an immunoassay. The immunoassay screens for the presence of different classes of drugs, including amphetamines, marijuana, PCP, cocaine and natural opiates. But there are several downsides of this type of testing. One is that it doesn't test for synthetic opioids and another is that it doesn't break anything down specifically.
In other words, it may show a positive result, but it doesn't tell you why the result is positive. Because of this, immunoassay drug tests are more likely to show false positives than the other type of urinary drug testing: gas chromatography/mass spectrometry. Unlike immunoassays, this test measures specific drugs. Instead of just giving a positive or negative result, it tells you exactly why the test showed positive and which drug or medication is causing that reading.
Because of this, the Centers for Disease Control and Prevention points out that gas chromatography/mass spectrometry tests are usually done to confirm (or refute) a positive immunoassay. This means that, if you think certain herbs, teas or beverages that you're consuming triggered a false positive drug test, you can request the more in-depth testing to pinpoint the cause of the positive and show that you're not partaking in any illegal substances.
Causes of a False Positive
Although immunoassays are convenient, a June 2015 report in Missouri Medicine notes that they are prone to both false positives and false negatives. However, herbs, teas and beverages aren't likely to cause a false positive. According to the CDC, the things that can cause a false positive are certain over-the-counter medications, a class of antibiotics called quinolones, which are broad-spectrum and used to treat a variety of bacterial infections, and poppy seeds.
Poppy seeds themselves are harmless, but the National Institute on Drug Abuse for Teens points out that morphine, codeine and heroin are all produced from the seeds of certain types of poppy flowers. Because of this, it's possible for you to have detectable levels of opiates in your system as soon as two hours and up to three days after eating poppy seeds.
However, the National Institute on Drug Abuse for Teens also notes that when positive test results are shown to be caused by consumption of poppy seeds with the more in-depth gas chromatography/mass spectrometry test, they are generally overturned. That being said, if you have to undergo regular drug screenings for work or school, it may be a good idea to avoid poppy seeds anyway, just to be safe and to avoid any confusion about your results.
Hemp-based products, like anything made with CBD oil and hemp oil, may also trigger a false positive. Although these products are legal in the United States, they do contain trace amounts of THC, so over-consumption may put your urine over the threshold for a positive result.
Medications and False Positives
In addition to poppy seeds triggering a false positive, it's also possible that certain prescription and over-the-counter medications can show up on a urinary drug test. These medications will trigger a positive on an immunoassay and then a gas chromatography/mass spectrometry test will be necessary to identify which medication is causing the positive. If you have a prescription for the medication, there's nothing to worry about.
A January 2016 report in the Journal of Analytical Toxicology lists some of these prescription medications, which include:
- Phentermine (an amphetamine-like medication that suppresses appetite)
- Tranylcypromine (an antidepressant)
- Propranolol (a beta blocker used for heart problems)
- Hydroxybupropion (an antidepressant and medication used to help people quit smoking)
- Trazodone (an antidepressant)
A report published in U.S. Pharmacist in August 2016 also lists over-the-counter medications connected to false positive results. Among these are antihistamines, analgesics (a class of pain-relieving medications), cough suppressants and heartburn medications. Nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, Aleve and Motrin can also trigger false positives. When you take allergy and sinus relief medications, like Sudafed, a false positive drug test is possible.
Safe Herbs for Drug Testing
While most herbs and teas are unlikely to trigger a false positive, there are herbs that are considered safe for drug testing because they've already been tested in depth. Of course, all of the herbs and beverages out there haven't been looked at individually, but researchers from a study that was published in the Jordan Journal of Pharmaceutical Sciences in January 2012 did analyze the effects of 31 of them.
After mimicking standardized urinary drug testing using urine that contained these substances, the researchers found that none of them triggered a false positive on a urinary test that screened for opiates, amphetamines and cannabinoids (like THC). These 31 herbs, spices and foods included:
- Beer's beach
- Hermon giant fennel
- Lemon balm
- Black cumin
Although herbs probably won't interfere with drug testing, if you're concerned about untested herbs, teas and beverages, stick to flavoring your foods with the tested herbs and spices and drinking teas with only those ingredients.
- National Institute on Drug Abuse for Teens: "Drug Testing for…Poppy Seeds?"
- Missouri Medicine: "Buyer Beware: Pitfalls in Toxicology Laboratory Testing"
- Jordan Journal of Pharmaceutical Sciences: "Effects of Herbs, Spices and Foodstuff on Urine Screen for Drugs of Abuse by Immunoassay"
- Centers for Disease Control and Prevention: "Urine Drug Testing"
- U.S. Pharmacist: "Urine Drug Screening: Minimizing False-Positives and False-Negatives to Optimize Patient Care"
- Journal of Analytical Toxicology: "One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry"