Hellow my question is how long does drugs stay on ur saliva. ?

Cant answer: Depending on the drug/medication it can remain your body for an "x" amount oc time. There are many variable to consider : what kind of drug? How is it and where it is metabolized? Sometimes how much and often you consumed it. By the way , drugs are not frequently tested in your saliva

It depends on the drug.: If you look up the drug and then look up the half-life of the drug you'll know when half of the medication is gone. Unfortunately all the medications can have different half-lives so there will be different times.