Urine drug tests are considered more accurate over salvia drug tests for a number of reasons. Urines drug tests have well studied and documented for 30 years whereas the saliva drug test is relatively new and thus less studied and documented. Whilst saliva testing definitely has its advantages, such as ease of collection, it’s reliability, accuracy, and drug testing variety are limited.
Avoiding detection with a saliva drug test can be as simple as brushing your teeth or using a mouthwash prior to testing can produce a false positive. So too by consuming food that can alter the pH levels can produce a false positive. There are few accredited laboratories that are authorised to perform a confirmatory test on oral fluids. The target drugs are present in oral fluids only by accident and in very low concentration levels compared to the concentration levels of the target drugs in urine as the body expels the drugs as waste.