With home drug testing methods believed to produce reliable and accurate results, many of us overlook the cases of false positives and draw conclusions on the suspect before reconfirming the result. But, researchers from the Boston University have found out that drug tests may produce false positives in 5-10% of cases and false negatives in 10-15% of cases.
There are so many factors that can impact the results of a drug test, especially home tests; so, it is better to be aware of the possible causes of false positives.
Home drug testing is usually done using samples like urine and oral fluids to detect the use of alcohol or illegal drugs like marijuana, cocaine, amphetamine, etc. The result of a test will be termed as 'false positive' when the test result shows positive for a substance which the subject under consideration has not abused.
Drug test kits detect the presence of drug metabolites in the sample by identifying the chemical structure of the drug. However, there are hundreds of over-the-counter legal medications, which have the similar structure as of illegal drugs. Lack of sensitivity of the drug test kits to differentiate almost similar structures of legal and illegal drugs, affects the results, thus producing false positive results. Even some foods can trigger this.
Medications and foods that cause false positive results
• Medicines for cold, anti-depressants can trigger this on tests conducted for amphetamines
• Painkillers and anti-depressants like Zoloft can show positive for benzodiazepine
• Taking antibiotics like Quinolone may result in false positives for opioids
• HIV medication, Sustiva can show positive for marijuana
• When it comes to food, poppy seed is very much effective in producing false results. Consuming foods with poppy seeds may alter your drug test results and show false positive results for opiates
Tips to avoid this false results:
If we really see, the majority of the medicines and foods that cause false positives are frequently used or consumed. Since the probability of using them is high, taking some precautionary measures can avoid the occurrence of false positives.
• Suspect should not use medicines before the test: As you are aware of the fact that medicines can cause false positives, ask suspect not to take any kind of medicines from 3 days prior to the scheduled drug test.
• Foods that should be avoided: As poppy seeds can alter the test results, ask the suspect to avoid foods containing poppy seeds, such as muffins and bagels.
• Second hand exposure to drugs: Consistent exposure to extremely concentrated second hand smoke (especially in case of marijuana and nicotine) may result in false positive results. So, ask the suspect to stay away from drug abusing friends before taking the test.
• Test procedure: One more important thing you should remember to get accurate results is to follow the test procedure carefully. Every home drug test kit will come with a brochure which clearly explains the test procedure. Especially, for the first time users, it is essential to study the booklet carefully before using the kit. For instance, while using urine drug test strips to detect drugs in the urine sample the results should be interpreted within 3-5 minutes after initiating the test. Ignoring this, may result in false positives.
• Test kit with broken seal: No matter from where you have bought your test kit, make sure that the seal of the test kit is not broken. Also check whether the kit contains all the items mentioned in the checklist on the outer box. All the testing tools should be in a proper condition.
It is always advised to use FDA approved drug test kits offered by reputed dealers. FDA approval confirms that the test kit is made of good quality material and no substance in the test kit alters or impacts the test results. Hence, in order to avoid false positive test results always go for reliable test kits.
