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Challenging Substances for Drug Testing Companies

  • By: Andrew Easler, Esq.
  • Published: Dec, 6 2014
  • Updated: Dec, 20 2022

If you’re going into the drug testing business, you need to be aware that there are some drugs that are very difficult to detect. There are cases, as well, where an employee might be using a drug that is illegal under most circumstances, but they have been prescribed that medication. This can create issues, as using the drug may impair their ability to do their jobs, but they’re not breaking any laws in using it.

For the drug tester, however, the real issue is going to be the ability to provide reliable testing for their clients. Here are some of the things that can be very difficult to detect in a drug test.


Cocaine is very difficult to detect if it is not tested for soon after use. For example, if an employee is using cocaine, it will show up in their urine anywhere from 2 to 5 hours after they use it, but it will only show up in detectable amounts for a total of 2 to 4 days after they have used the substance. If it is not found within that time, a hair test will show evidence of the drug’s presence for 90 days after use, but urine and saliva tests will reveal no usage.


Heroin is another particularly dangerous drug that can be difficult to detect. It remains in the urine for 2 to 4 days after it has been used. It will also remain detectable in the hair for 90 days after it has been used, but won’t show up for a full five days after the user has taken it.


LSD requires specialized testing to detect. It won’t show up in regular drug screening methods, which means that it is something that people are more likely to indulge in if they’re simply trying to dodge a test. If you need to test for LSD, it requires a more expensive, specialized option.

Common Drugs

Marijuana is detectable in urine for anywhere from 15 to 30 days after it has been used. It’s detectable in the hair for 90 days after it has been used, making this a very easy drug to screen for.

Unfortunately, alcohol moves through the body very quickly and is very difficult to detect. When abuse is noticed, it is usually through employee performance and behavior more than anything else.

If you plan on providing regular or mobile drug testing services, always inform your clients of how long a given drug remains in a user’s body and how likely it is to be able to be detected.

The information on this page may have changed since we first published it. We give great legal advice, but this page (and the rest of our site) is for informational use only and is no substitute for actual legal advice. If you’d like to establish an attorney-client relationship, reach out to us and we’ll tell you how we can make it official. Sending us an email or reading this page alone doesn’t mean we represent you.

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