While a large number of these topicals feature very little THC, many users are worried about the potential risks that accompany them and whether they could trigger a positive result on a drug test. These are just a couple of the challenges faced by patients using marijuana to manage pain in a society still largely unreceptive to their needs.
With topicals unable to get users high, it would stand to reason that it’s not possible to fail a drug screening as a result of their use. In principle, this is true; but there are some caveats. This study from 2017  confirmed that topicals containing THC did not cause a positive test in both blood and urine.
WHAT ARE TOPICALS?
“Topical” is a term used to describe products applied to the surface of the body. Balms, ointments, lotions, and salves are all included in this category. What makes them unique is that rather than being consumed orally, they are applied directly to the skin. For that reason, they are not taken as a recreational drug, but instead for exclusively therapeutic use.
With a localised application, sufferers can target specific areas of trouble, supporting mild pain relief and reducing inflammation. It is the nature in which they are absorbed through the skin, however, that has raised questions about their safety. Will users get high as a result? And furthermore, would that cause a positive reading on a drug test?
The caveat is transdermal patches. These work in the same way as a nicotine patch, providing patients with a strong dose of the active ingredient that is absorbed into the bloodstream through the skin. As such, use of THC-rich cannabis patches is likely to result in a failed drug test.
However, depending where you live, there might also be transdermal patches on the market. These work similarly to nicotine patches and do contain components that allow the THC to break into the bloodstream and will cause intoxication and a positive drug test.
Amanda Reiman, PhD.
Think about rubbing alcohol. You can rub it on various places on your body, but you will not feel intoxicated or have a BAC over the legal limit if you use it, even though it has a very high concentration of alcohol in it. However, remember that, like the transdermal patch, consuming marijuana in other ways will show up on a drug test.
The topicals I am referring to only include lotions, balms, salves, and others products that contain cannabis and are rubbed on the skin.
Whether you support the idea of drug testing or not, the consequences of having a positive test can be far reaching and detrimental.