How long does vicodin stay in your system?

Vicodin stays in the urine for 2 - 4 days

In the saliva for 12 - 36 hours and in the hair for up to 90 days.

It is unknown exactly how long it says in the blood or sweat.

But of course as long as you have your prescription, merely tell the person doing the test that you have one. You should not fail the test if you provide proof you are talking it legally.