Drug tests are often administered only once when you're applying for a new job or entering a new program at certain schools. However, they can also be part of a routine if you're on parole or in a drug recovery program. A false-positive usually occurs when the individual is taking a legal medication with similar properties to the illegal drug in question, causing the test to show positive for the illegal substance.
Ephedra, also known as ma huang, is a type of herb whose derivatives are used extensively in over-the-counter medicines. Some of this herb's chemical derivatives include ephedrine, pseudoephedrine, desoxyephedrine, propylephedrine and phenylephrine. Any medication that includes one of these ingredients could cause a false-positive for a methamphetamine drug test. Common medications with these ingredients are cold medicines and nasal decongestants, such as Sudafed, NyQuil, Vick's Inhaler and Dimetapp.
Many of the over-the-counter drugs that are used to treat ADD and ADHD have components that are similar to those found in methamphetamine. Ritalin, Adderall and Dexedrine may all cause someone to have a false-positive drug test for meth. The use of Dexedrine (Dextroamphetamine), Ritalin (Methylphenidate) and Adderall (made of four different amphetamine compounds) should be put on hold if you are aware that you have an upcoming drug test.
Any over-the-counter diet pills containing phenylpropanolamine such as Accutrim or Dexatrim can cause a false-positive for meth. Other diet pills may contain ingredients made from Ephedra, so check to make sure that none of the derivatives listed in that section are included in the ingredients of your diet pills as well.
Various different asthma medications can cause false-positives for meth, including Primatine tablets, Bronkaid tablets and Marax. If you depend upon these pills for general health, it may be necessary to do a more extensive toxicology test on the sample to determine exactly what is causing the positive test result.
A kidney infection, kidney disease, liver disease and diabetes could all cause a false-positive for methamphetamine. This could be due to the fact that individuals with these problems may metabolize chemicals in their bodies differently, possibly resulting in a buildup of chemicals.