I verbally accepted a summer internship offer and expected a urine drug test to be required. However, the official offer states the drug test is a hair test, which goes back roughly three months. I have used THC-containing products a few times over that period, not so much that I wouldn't pass a urine test but enough that I expect to fail a hair test.

My test will probably be within the next month. As a backup plan, I have obtained a medical certification approving my use from my state's department of health (a "green card"). As I understand it, a company could potentially rescind an offer after a positive drug test for THC metabolites, even if the person has medical approval. This could potentially be considered discrimination, and there have been lawsuits over this (clarified in the comments). I believe the case law is still developing (in my state at least) and no outcome is certain. I would rather avoid a complicated legal dispute if possible. All I want to do is work the job I was offered.

A friend of mine pointed out that the employer might not even be testing for THC products. It might be a long shot, but it would certainly help my stress if I knew.

Edit: My attempt to provide context may have obscured the question. Feel free to ignore my specific situation and answer the question itself (which may perhaps help others in the future).

The question: Is it reasonable to ask what substances are being tested for? What's the likelihood of getting an answer, and could trying have any negative repercussions?

Side question, not the main point: Additionally, I'd be very appreciative of any insight on whether it would be a better move to mention my green card up front or only in the case of a positive test result.

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    If the lab is external to the company you may be able to research the type of drug testing that is done, or by calling the lab directly
    – Noel
    Mar 25, 2022 at 23:31
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    If you know the name of the lab, have one of your extroverted friend call the lab or visit in person, and ask questions. Mar 25, 2022 at 23:58
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    There is always the shaving option. They can't go back 3 months if there isn't 3 month's worth of hair growth to select from.
    – jwh20
    Mar 26, 2022 at 0:19
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    Also, the most practical "backup plan" is to continue applying and interviewing with other companies (until you get the tests back at the minimum). Don't stop doing that. Don't stop your momentum of looking for a job. Litigation is not a good backup plan. Even successful litigation can take several years to resolve (and honestly, I really doubt that you'd win anything). Mar 26, 2022 at 2:46
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    @jwh20 they can also take hair from elsewhere on your body (so you better shave everything), or nail clippings. Or they could just say "you're clearly trying to cheat the test, goodbye".
    – Gh0stFish
    Mar 26, 2022 at 15:26

3 Answers 3


You can ask, but most of the ways of asking will make it pretty clear that you've taken some drugs and are wondering if they'll show up - especially if you're asking a specific substance. If you pitch the question more as "I've never done one of these tests before, how does it work?" then that's less obvious - but it may not answer your question.

When you take the test, you'll most likely be asked to fill out a form listing all the drugs that you've taken over the last 3+ months (including standard prescription and over-the-counter ones), so you should include it there.

The simplest thing to do is to speak to HR at the company, explain that you use certain products for medical reasons (with approval) which are likely to be flagged on a drugs test, and that it in no way impacts your ability to work/drive/etc. Doing this before your drugs test makes you look proactive and open, and means that you have a chance to explain it (which you may not get otherwise - they could just immediately reject you on a positive test result).

If they decide not to hire you on that basis then that sucks, but you've saved everyone time finding dealing with it up front.

  • Well, there was a time when they would have found morphine in my blood stream... It helps when two strong men rearrange some broken bones in your leg while you're awake.
    – gnasher729
    Mar 26, 2022 at 15:31

Something to keep in mind, depending on the type of job worked, is that there may be a policy of conducting this test as part of every job hire and background test, but they may decide to hire you anyway.

Same as, when they run your employment history and can't verify a piece of information, it's not an immediate 'cant hire', it's just another item that gets added to a report and submitted to the hiring manager.

Even if you're positive on THC I would think there's a chance you still get hired. May have some eyes on your performance though

  • Thank you. I'm hoping this is a possibility, but I can't see a way to know. Judging from the downvote, apparently someone thinks this is not likely? Mar 26, 2022 at 12:32

If you don't have a contact you can ask. Then just assume they'll test for THC and stop worrying about it.

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    @JoeStrazzere yeah, my advice is to relieve the stress. I don't give advice on fooling drug tests.
    – Kilisi
    Mar 26, 2022 at 11:29
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    The question is it not how to fool a drug test, it is whether it is appropriate to ask someone in the company (such as a recruiter) what drugs are tested for, and the likelihood of this yielding useful information and/or repercussions. Neither of the two answers have actually answered this, so perhaps I did not write the question clearly enough. Hopefully it's clear now. Mar 26, 2022 at 12:34

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