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Does Second Hand Marijuana Smoke Show Up In A Blood And Urine Test?

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Posted on Mon, 26 May 2014
Question: I was exposed to second hand marijuana smoke on an outdoor patio. I have a blood and urine test in two days. Should I be worried?
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Answered by Dr. Jonas Sundarakumar (47 minutes later)
Brief Answer:
Very unlikely to fail the test...

Detailed Answer:
Hello and welcome to Healthcare Magic. Thanks for your query.

I understand that you are concerned about the second hand exposure to marijuana and the upcoming drug test in two weeks.

Firstly, the amount of marijuana absorbed into the system as a result of second hand exposure is usually minimal.

Secondly, the average drug detection time for marijuana is only about 1-2 days with a blood test and about 7-10 days with a urine test.

So, considering the above two facts, it is very unlikely that you will fail the drug tests after 2 weeks. But you have to ensure that you don't get exposed to any more marijuana before the tests.

Wish you all the best.

Regards,
Dr. Jonas Sundarakumar
Consultant Psychiatrist
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Follow up: Dr. Jonas Sundarakumar (59 minutes later)
The drug test is in 2 days not 2 weeks (Tuesday morning). I was exposed Saturday night. I took an over the counter urine test today, Sunday, and it came up with a very faint line. The instructions said that a line no matter how faint is negative but I know that over the counter tests are at 50ng and an actual test is lower. So, should I be worried? Also, from your reply am I to understand that the blood test is more or less likely to test positive?
Thank you.
doctor
Answered by Dr. Jonas Sundarakumar (1 hour later)
Brief Answer:
No need to worry...

Detailed Answer:
Hello again,

Sorry about the confusion regarding no. of days...

Regarding the home drug test that you have done, it is true that a faint line is indeed considered as a negative result.

Now, the "cut-off" value for THC (the chemical / metabolite which is screened for in testing for Marijuana) can vary from lab to lab, but most government-approved tests have a standard cut-off value of 50 ng/ml. So, if you have passed an over-the-counter test today, it is highly likely that you would pass the upcoming actual test after 2 days.

Another very important factor which makes a difference in passing drug tests is the frequency and quantity of use. Though I had mentioned that "on an average" it could be detected in urine for upto 7-10 days, for a single-time, mild user, the drug detection time is much lower - usually only 2-3 days.

In your case, since you have been exposed only to second hand smoke, the amount of the drug entering the system would be relatively much lower, and hence, is likely to get cleared within a couple of days. So, in my opinion, you needn't worry about the upcoming tests.

Blood tests have a much lower detection time (of 1-2 days) than urine tests. So, in your case, the chances of detection are actually lower with a blood test than with a urine test.

Regards,
Dr. Jonas Sundarakumar
Consultant Psychiatrist
Note: In case of any other concern or query related to prevention, evaluation, diagnosis, treatment, or the recovery of persons with the any type of addiction or substance use, follow up with our Addiction Medicine Specialist. Click here to book a consultation now.

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Jonas Sundarakumar

Psychiatrist

Practicing since :2003

Answered : 2190 Questions

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Does Second Hand Marijuana Smoke Show Up In A Blood And Urine Test?

Brief Answer: Very unlikely to fail the test... Detailed Answer: Hello and welcome to Healthcare Magic. Thanks for your query. I understand that you are concerned about the second hand exposure to marijuana and the upcoming drug test in two weeks. Firstly, the amount of marijuana absorbed into the system as a result of second hand exposure is usually minimal. Secondly, the average drug detection time for marijuana is only about 1-2 days with a blood test and about 7-10 days with a urine test. So, considering the above two facts, it is very unlikely that you will fail the drug tests after 2 weeks. But you have to ensure that you don't get exposed to any more marijuana before the tests. Wish you all the best. Regards, Dr. Jonas Sundarakumar Consultant Psychiatrist