Does Second Hand Marijuana Smoke Show Up On A Drug Test?

A commenter asked a great question on one of our older posts.  That question was, does second hand smoke affect the result of a drug test?  It wouldn’t be fair if it did, of course.  As the commenter points out, (medical) marijuana is legal in some states, and if you are not smoking it, you should not be punished for having been around second hand smoke.

The good news is that none of our home drug test kits (hair, urine, or saliva) will pick up exposure to second hand marijuana smoke as a positive result.  Here is what the test manufacturer said on the subject:

“It [second hand marijuana smoke] would not register on our tests.  We had a test where someone was placed in a isolated room with THC smoke was being pumped in for 24 hours straight and the person did not register.  On a lab test it did pick up about 3 or 4 nanograms but as you know instant tests are set at 50ng/ml.”

Does second hand marijuana smoke affect our drug tests?

Even at the confirmatory GC/MS lab urine drug test level of 15 ng/ml, you would still not test positive for marijuana due to second hand smoke.  The cutoff level for the saliva drug test is 100 ng/ml (so again, second hand smoke would not produce a positive).

When it comes to hair, the manner in which the lab analyzes your sample makes external contamination impossible.  Hair drug testing labs only detect the metabolite of marijuana, THC-COOH.  This is only produced when marijuana directly enters the body (and not through someone’s second hand smoke, which is indirect) and is broken down by the body.  The hair test will not pick up contaminants from the outside.

So, even if you have been exposed to second hand smoke, if you have not yourself smoked you should be safe with our tests.  Thank you to our readers for such great questions and I look forward to more in the future!


  1. hector says:

    does 2ndhand marijuana smoke show up in pee test?my po officer made me take 1 2day.

  2. admin says:

    Hi Hector,

    Second hand marijuana smoke should NOT show up on your marijuana urine drug test. Tests have been run on the kits we sell that prove this. A test could pick up 3 or 4 nanograms, but that is under the cutoff level of both a preliminary and confirmatory test, for just this reason – to reduce the chance of false positives.

    Thank you for your question and please feel free to contact us at 1-888-448-5657 or with any other questions!


  3. ricky says:

    Ok so I’m scheduled to have a piss test in like 3 days but like 2 weeks ago I been around people who smoked but it was outside but I think I inhaled the smoke not sure but as I moved away as soon as I smelled it. And I don’t know how strict the piss test is for the armed service. I have been running and exercising drinking a lot of water but I’m just paranoid. Never smoked

  4. admin says:

    Hi Ricky,

    Thank you for your question. Drug tests are, particularly at the initial screening level, designed to screen out second-hand smoke positives. In the case of such incidental/light use as accidentally inhaling marijuana smoke, it should be out of your system within a week. The more frequent marijuana use is, the more it builds up in the system, and the harder it is to release it (thereby lengthening the detection time).

    Thanks and good luck,


  5. dylan says:

    I am trying to get a job at a place in my home town and they do hair tests. About a month ago i was at a party and I was drunk, somebody gave me a cigarette well soon to find out it was marijuana. Is there any way to try to pass this test?

  6. admin says:

    Hi Dylan,

    The hair drug test is very difficult to beat because they test the inside of the hair. If you only tried it once it is possible it will not show up. Marijuana does not show up as well in hair as it does in urine. The only thing we can really say is take the test and find out; then you can make a decision about whether the job should be pursued or not.



  7. big jim says:

    so i quit smoking weed for 2 months and after that smoke 2 more time and it been a month sence i smoked but my friends still smoke and last week i was with him and he started to smoke will i put my head out the car so i wont smell it but it was strong smell and now im having a saliva test coming up do you think it will show

  8. josh says:

    I was at a party last saturday having a smoke on the porch. There was a couple people smoking a joint and the wind blew the second-hand smoke in my face. I quickly put out my cigarette and went back inside. Besides the fact that I smoke cigarettes when I drink, I’m a pretty healthy guy. I drink plenty of water and workout everyday. I have a pee test coming up for my new job this week. What are the chances of testing positive?

  9. Tom says:

    Okay, so my friend was being a d***, and closed off all airways in his room and smoked for a LONG time… Will it show up on a home drug test? (Hotboxing)

  10. edgar says:

    I have not smoke in 30 days but last Friday my friend was smoking so I decided to take a shot gun him blowing smoke n I inhaled will that appear in a UA test. N how long will it take to get clean.

  11. admin says:

    Hi Josh,

    Thank you for your question. Second hand smoke should not show up on your drug screen, as the tests are designed to rule such things out. In fact, our test manufacturer writes:

    “We had a test where someone was placed in a isolated room with THC smoke was being pumped in for 24 hours straight and the person did not register. On a lab test it did pick up about 3 or 4 nanograms but as you know instant tests are set at 50ng/ml.”

    On a typical pre-employment screen, you are not going to be tested at 3 or 4 nanograms, you will be tested at our cutoff level, which is 50 ng/ml (jobs with security clearances, the military, etc. may test at lower cutoff levels, but 50 ng/ml is recommend by the US Department of Transportation for drug testing). Whiffs of second-hand smoke are not going to show up.

    Thanks and let us know if you have any other questions!


  12. admin says:

    Hi Tom,

    Please see my comment to Josh above. You should be fine. As our test manufacturer says:

    “We had a test where someone was placed in a isolated room with THC smoke was being pumped in for 24 hours straight and the person did not register. On a lab test it did pick up about 3 or 4 nanograms but as you know instant tests are set at 50ng/ml.”

    Essentially they ran a hotbox test and the test would not pick up the person who absorbed the second hand smoke.

    Thanks for your question and let us know if you have any others!


  13. admin says:

    Hi Edgar,

    I am not really clear on what you mean by shot gun but if you smoked marijuana you are at risk of failing a drug test. If you don’t smoke again it should be out of your system in a week or so. Marijuana accumulates in the fat cells so if you smoke a lot and quit on Friday, it’ll still be in your system 3 weeks from now. If you smoke only a little and stop on Friday, you could be clean by next Friday.

    The only wild card is whether your body was detoxed completely from smoking in the past 30 days. If you are concerned I do recommend getting a few THC drug tests from us to find out if you are positive or negative. I say this because of the unusual way marijuana metabolizes in the body.

    Thanks for your question and please let us know if you have any more questions!


  14. shorty says:

    The last time I smoked was about 2months or more ago. I have heard that pot cleans out of one’s system depending on their exercising and eating habits and even depends on their weight and how fast the metabolism works. I weight around 200 pounds (I am a big mama) my height is 5′ I haven’t exercised in like a moth (that why I gained so much weight) but I do drink a lot of green tea and water. 2 days ago I took a pee test for a job do you think this will affect my test results????

  15. jane says:

    I have been with a partner for more than 7yrs now and they are a full time smoker, due to me being around them for more than 18hrs a day over the pass 7yrs could this effect a saliva drug test?

  16. Dee Dee says:

    I am taking a drug test for a new job and my boyfriend smokes marijuana at night while I am in the room. at least 1x a day 5 nights a week.

    Do I have to worry about taking a hair follicl test or urine test?


  17. admin says:

    Hi Dee Dee,

    Second hand smoke should not show up on a hair or urine drug test. In the case of a hair drug test, the tests are designed to exclude “external contaminants” such as second-hand smoke. In the case of urine testing, see this comment above for an explanation of why second hand smoke will not show up.

    Hope that helps! Thanks for your question.


  18. Emilee says:

    I was around some people smoking & they “hot boxed” you would say. I was wanting to know if that will show up on a urine drug test. & Also, I wanted to know if you drink just a little bit.. Will it show up, too?

  19. BigB says:

    I have not smoked in 28 days or so, and wasnt a heavy smoker before that. i was around friends who were smoking a blunt in the room and i was in the proximity, the windows were open but i still could strongly smell the marijuana over the cigarette i was smoking. they smoked for close to 10 minutes then put it out. I bought a at home drug test and took it the morning after that happend and it came back negative. I have a drug test this weekend that will test at 15 ng. i know i passed the 50 ng but If i run and excersice often this week i should still be under the 15 ng level by the weekend, is that correct? i am an athletic person in good shape with not much fat, under pretty tall and under 200 pds

  20. Vince says:

    Hello, I am being ask to take a hair-based drug test. Probably 2-3 months ago, I smoked a small amount of marijuana, 2 puffs. I do not use any other drugs and prior to this instance, I had not smoked marijuana in about 3 years. I am 39, and in good health. I am very nervous about this test and how it may affect my future (or lack thereof) with this company. I would greatly appreciate and value any comments/suggestions.

  21. admin says:


    You should be fine. Our test does not pick up second hand smoke (see above). A marijuana drug test would not detect alcohol use. There are urine tests that detect alcohol, you can read a bit about one of them here:
    Thanks for your comment!

  22. admin says:


    This comment should answer your question. I think you would still be under the 15 ng level.

  23. admin says:

    Hi Vince,

    I would say the drug will probably not be detected in the hair. Hair drug tests are designed to catch drug abuse, not incidental drug use. When it comes to marijuana (and this only applies to marijuana), there is the additional issue that a hair drug test may be unable to detect the THC metabolite due to the fact that the metabolite was unable to bind with the hair shaft. This can be caused by the type/quality of the marijuana smoked/ingested, or by what it has been mixed with, e.g. tobacco. As a result, the result for marijuana may be negative. This is only the case with THC and not with the other illicit drugs (Cocaine, Heroin..etc).
    I hope this answers your question. Thanks,

  24. GeoV says:

    I was at my friends home yesterday and a group of my friends decided to smoke in the garage. I was exposed to 2ndhand smoke for about 3-5 minutes (light smoke) then I went inside. Then On the drive home my friends smoked and I was exposed for about another 2 minutes of light smoke. I have a MEPS physical thursday. Will this show up on the Urine Exam even though I didn’t smoke?

  25. Linda says:

    I have a boyfriend who recently smoked about an small cigarette (NO LONGER THAN 3 INCHES) of pot on SAturday. He was drug tested on Monday for a new job. Is there a possibility he will fail. Also he has been taking Motrin a lot due to his injury on his hand. Will this cause a positive test?

  26. admin says:


    Don’t worry about the second hand smoke. You would have to be in a room with marijuana smoke pumping constantly for 24 hours to have a positive based on second hand smoke alone. You should be fine on your test.

    Thanks for your question!


  27. admin says:

    Hi Linda,

    Thanks for your question. The Motrin will not affect the marijuana test in any way. The marijuana from smoking on Saturday will probably cause him to test positive. Marijuana if you do not smoke regularly at all will stay in your system for about 3-7 days. But if it’s not just one cigarette or if you smoke regularly/daily/multiple times daily, marijuana stays in the system for a much longer time, up to 45 days.
    Hope this helped. Thanks again,

  28. Mike says:

    will you test positive from bodily fluid of someone who have smoking marijuana.

  29. brianna says:

    Hello i was with my boyfriend one niqht (dec. 17) and he beqqd me to qive him a shottqun (blow smoke in his mouth) he has a u.a on jan 6th. will he come up hott.? please let me know. thank you.

  30. dre says:

    second hand smoke was blown into my mouth twice 4 days ago will I pass a urine test tomorrow?

  31. admin says:

    Hi Mike,

    Thanks for your question. Bodily fluids shouldn’t affect a drug test. Thanks, R

  32. Heather says:

    I inhaled marijuana once or twice on Sunday or Monday night and underwent a urine drug screen on Friday. I am an infrequent smoker and when I do it is usually passed to me by my husband. Meaning I rarely put my lips on the pipe. What do you think my result will be?

  33. admin says:

    Hi Brianna,

    Your boyfriend should be fine. If he does not smoke marijuana frequently it should be out of his system within a week at most. If he was smoking a lot before that day he might show up positive on a urine test, but that would be more to do with all the built up THC in this body than that one hit. California’s NORML page is a great resource for understanding exactly how that works, and we addressed the question of “how long does marijuana stay in your system?” elsewhere on our blog too.


  34. Nene says:

    My husband smokes oftem at home n it fills the house im 36week pregnant n dnt wanna lose my baby shuld I be worried

  35. admin says:

    Hi Nene,

    Unfortunately we aren’t qualified to answer that kind of question. I would suggest asking your doctor.


  36. Lynn says:

    I am 37 weeks pregnant my husband and his friend are always smoking in the same room with me i always try to stay by a open window. I’m worried though its going in my system I was told by a friend that the hospital tests you before you go home with the baby will it be in my system?

  37. admin says:

    Hi dre,

    Thanks for your question. In the case of one person blowing smoke into another person’s mouth (what’s called “shotgunning”) it’s actually not the same as second hand smoke at all. Having someone inhale from a joint or bong, and then blow into your mouth, is very potent. It contains much much more THC than second hand smoke does, and you are probably absorbing more THC than you would if you were just smoking a joint. So it’s very possible that you would fail a urine marijuana test in this instance. If you have never smoked before and this was your first time, it could still be in your system, even though 5 days have passed. If you are a frequent smoker then you are having to deal with an extended detection time anyway due to THC building up in your system.
    In any case, having someone breathe smoke into your mouth can cause you to be positive on a urine test.
    I hope this answer was helpful! Thank you for your question,

  38. admin says:

    Hi Heather,

    It doesn’t sound like you inhaled very much. Considering that if you infrequently smoke it takes about a week for the THC to be out of your body, your test may have a somewhat fair chance of coming out negative. But…you did only give it three days (Tuesday, Wednesday, Thursday) to clear out of your system. I don’t really know what you mean by “passed to me by my husband.”

    So much depends on your own metabolism and smoking history. This is why we recommend people test if they are concerned in this situation.


  39. ryan says:


    I have recently quit smoking weed about a week ago. I did this because of the future chance of a drug test. This could be months away. My roomate still smokes in our apartment and I was wondering if that would cause the thc to stay in my system longer.

  40. Desi says:

    Hi Robyn, quick questions for ya, I was at a xmas party Dec 23 2010, and few friends made me take one hit of weed….. I have never touched drugs in my life. I just had a urine and hair drug test done 01/28/2011(35 Days Later)….I dought the urine test will find anything, but im worried about the hair test. Will one hit show in a hair test?

  41. Bossblunt says:

    I smoke a lot of spice and was at a party last night. A lot o people were smoking weed outside and I was with them smoking spice Whig is undetectable. I get urine tested in the next 3 days but passed one I took a little less than a week ago and I have not smoked weed since then. Should I be worried about failing?

  42. sheena says:

    hi i did a shot gun like 1 to 2 weeks ago whats a shot gun? it’s when someone smoke and then blows in in your mouth and you inhale it will i fail my drug test for the navy.

  43. PassiveSmoker says:

    Hi Robyn,

    My apartment mates smoke weed every day! and this has been happening for almost a year. Will this show up on a urine test ? I am really concerned. I have tried to stay away from their room for a while now and I myself have never given into the temptation. What do you think about it ? Should house for the next week else where just to be sure.


  44. admin says:

    Hi Sheena,

    A shotgun is basically like a concentrated hit of marijuana – like taking a bong hit or something. If you smoke weed regularly and only recently quit it might still be in your system a week or two after quitting. I believe the initial screening level for marijuana in the DoD is still 50 ng/mL, the same as our marijuana urine tests. So you could always buy a drug screen and find out. Learn more about the DoD’s drug testing rules here.



  45. admin says:


    No, it shouldn’t be a problem. Urine tests are not designed to pick up second hand smoke. As it says in the article, even if smoke is pumping into a room for 24 hrs a day, only 3 to 4 ng of THC show up. That’s way below initial screening levels. It’s even below confirmatory screening levels.


  46. admin says:

    Hi Ryan,

    Second hand smoke should not affect a urine or hair drug test. Double-checking the saliva test right now.



  47. admin says:

    Hi Ryan –

    Second hand smoke won’t affect a saliva drug test either. That’s the answer from our manufacturer.



  48. […] Actually taking a shotgun hit is like taking a very concentrated hit – it’s comparable to taking a bong hit as opposed to smoking a joint.  It’s very potent and contains a lot of THC.  Second hand smoke is just ambient – the THC dissipates into the air rapidly.  That’s why second hand smoke doesn’t appear on a marijuana drug test. […]

  49. Mom Of Three says:

    Hi Robyn,

    Is there any kind of test available that would pick up second hand marijuana smoke? Long story short, my ex smokes around my two oldest when they are with him for the weekend, but he denies it, so I wanted to drug test the kids when they came home to prove that he is lying and is endangering the well-being of the kids. Does such a test exist?

  50. Mom Of Three says:

    Thanks by the way. 🙂