How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Family Physician Your Own Question
Family Physician
Family Physician, Board Certified MRO
Category: Drug Testing
Satisfied Customers: 12816
Experience:  Medical Review Officer - Physician Trained and certified in drug test interpretation
Type Your Drug Testing Question Here...
Family Physician is online now
A new question is answered every 9 seconds

how far back do oral saliva drug test detect thc

Resolved Question:

how far back do oral saliva drug test detect thc. this will be lab tested.
Submitted: 5 years ago.
Category: Drug Testing
Expert:  Family Physician replied 5 years ago.
Saliva tests for marijuana (THC) have a very short detection period. Generally they are negative within 12-24 hours even when testing is performed by a laboratory.

Urine testing has a longer detection period 3 days after a single use, but saliva is very short. This is one "advantage" of this testing, since it correlates better with impairment; the detection period is not much different than the period one might be considered "under the influence".
Customer: replied 5 years ago.
is there anything that can be done to insure this test will come back negative? can you tell me how you came to this answer of 12 to 24 hrs personal knowledge or reference.
Expert:  Family Physician replied 5 years ago.
The way to insure that your drug test is negative is to not use marijuana for at least 24 hours before any test. Obviously, the longer the better.

As for references:
From Quest Diagnostics

Family Physician and other Drug Testing Specialists are ready to help you

Related Drug Testing Questions