With many employers making use of random drug testing in the work place, employees sometimes wonder about the possibility of registering a false positive on a drug test. The fact is, there are a number of different over-the-counter medications, foods, vitamin supplements, and even prescription medicines that can cause a false positive. It's important for employees to let their employer and the testing facility know if they have taken any medicines that might affect the results.
Among over-the-counter medicines, many of the night-time cold medications people use to minimize cold and flu symptoms for the evening can cause false positives. This is particularly true of the liquid cold relievers, as many of them contain various members of the ephedrine family. Some weight loss products also can cause false positives, as can some nasal sprays and asthma medications.
Certain foods can sometimes result in a false positive on a drug test. Many people are familiar with the fact that poppy seeds can throw off the results by showing up as an opiate. These seeds are often used in salad dressings, as an ingredient in many casseroles, and as an added topping on buns and rolls.
Vitamin supplements may also cause a false positive. Riboflavin, also known as B2, may return a false THC reading. Along with being part of most B complex vitamin supplements, riboflavin is found in hempseed oil and also as a stand alone supplement. Many herbs that contain moderate to high amounts of B vitamins may also register a false positive on a drug test.
Prescription medications, including antibiotics like ampicillin and amoxicillin, can cause problems as well. Many prescription pain medications will show up on a drug test since they can contain ingredients that are related to some illegal drugs. Even some anti-anxiety medications can cause a positive result. Some diseases, such as diabetes, liver disease, and kidney infections, may even register as opiates on drug tests.
When preparing for a drug test, individuals may want to provide a list of any medications taken recently, as well as vitamins and any herbal supplements, to the testing facility and the company's human resources department. If the person undergoing the drug test has an ongoing medical condition, that information should be provided also. This can make a huge difference in evaluating the final results of the test.