Understanding the difference in Cannabis detection between urine and saliva drug testing kits.

Saliva drug tests only detect parent THC residues, left directly in the oral cavity when smoking.

Urine drug testing kits detect both parent THC and COOH metabolites or breakdown products being excreted in urine.

The above makes an enormous difference to the test results you get using the 2 methods.

Let's consider a previously clean individual who smokes Cannabis at 8 pm.

By 8.01pm a saliva cannabis drug test will be positive. A urine cannabis drug test will be negative, and may not give a positive result for over an hour.

The individual finishes smoking cannabis at 8.15 pm 

If they fall asleep, a saliva test may still just be positive at 8.00 am the following morning.

If however, they decide to eat a curry, 2 pints of larger and brush their teeth and rinse well, the saliva test may likely show negative after any of the above actions.

Urine drug testing performed after 24,48,72 and 96 hours would all likely give positive results.


The above examples highlight the differences between the 2 very different tests.

Expecting saliva test kits to perform in the same way as traditional urine cannabis test kits is simply not realistic.

The major advantage of saliva testing for cannabis is that it can be performed in any location, even at the roadside. Saliva testing ONLY targets recent significant THC exposure, versus historic, older THC exposure and this is why the use of saliva THC screening is increasing in workplace testing, where the duty of care emphasises the need for a safe and drug-free workplace.

If however, you want a Cannabis drug test which will detect if any Cannabis has been used over the last few days, you definitely need a urine drug testing kit.

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