There is a large variety of different body supplements, it is hard to say which ones could result in a false positive. Many of these supplements advertise that they are all natural, unfortunately some all natural herbs can give you a positive result. Some supplements include ephedrine or other ingredients that are found in methamphetamine. These ingredients may boost energy, but depending on the quantity you are taking, they could cause a false positive for drugs. Unfortunately, drug tests are not 100% accurate. There are other drug testing methods that are more accurate but are much more expensive.
Some of these products are produced in plants that make other supplements, and there could be cross contamination involved. You may not have voluntarily taken a substance that gives a positive result, but because the all natural supplement you took came in contact with an illegal one, you may get a positive result.
Supplements high in Riboflavin can result in a positive THC test. THC is found in marijuana. B vitamins taken in high doses can cause a false positive. B vitamins are a very common vitamin found in supplements because of their energy boosting qualities.
Prescription medicines and some over the counter medicines can cause false positives on a drug screen. Usually, if a test shows a trace of a chemical that could be considered illegal, the drug testing company will call you. They will simply ask what medications you are taking. Be honest, and tell them the brand and dose of supplement you are taking. They will not tell you any other information. They take into consideration the supplements and make the determination if it is a legal product or not.
There are many foods that may contain chemicals that can register a positive as well. Read labels on your food products and any supplements you may take. If you see anything that may cause a positive avoid it and move on to another one. There are several websites that have full lists of prescription and over the counter medicines that may cause false positives, as well as some other ingredients that you may find in supplements. Do your homework, and research any supplement, compare the ingredients against the list to determine your risk of having a false positive.