Determining amphetamine use by saliva testing has a much shorter window of detection time that detecting the use of amphetamines with a urine test.  The saliva test for amphetamines is mainly conducted to determine a very recent use of the drug and will not determine any long term use.

On average for a single use of amphetamines the saliva test can only detect the presence of amphetamines for up to 72 hours.  The cutoff level for the presence of amphetamines in saliva is fifty nanograms per milliliter.  Anything below this level can be considered a false positive for the use of amphetamines.  Some antidepressants can be mistaken for the use of amphetamines in routine drug screening.  The use of a Vicks inhaler can trigger a false positive for methamphetamine use.  Many over the counter cold medications that contain ephedrine and pseudoephedrine on a routine drug test but may be determined that the person was not using methamphetamines when the sample is scrutinized by more sophisticated spectrometry testing.  Many pharmacies across the country have moved some cold medicines back under direct pharmacists control because some of these cold medicines are used in the manufacturing of methamphetamines.

Other prescribed medicines such as Adderall or Dextrostat that are used to treat diseases such as Parkinson’s disease and ADHD with register a false positive on a saliva or urine test for amphetamines because they are actually amphetamines but prescribed legally.  Another popular drug which can test similar to amphetamines is ecstasy which is a processed form of amphetamine.  If a saliva swab test for amphetamines turns up positive then a further test will be conducted to determine if it is a false positive or not.