The short answer to the question of whether HHC will show up on a drug test is yes, most likely. Marijuana tests don't detect HHC, but it is chemically similar to THC and is metabolized to many of the same compounds, including THC-COOH, which is one of the main markers used to detect THC in a blood, urine or saliva sample. Each person has a slightly different natural concentration of CYP3A4, making them more or less able to process HHC. Even if your test certificate indicates otherwise, the detection limits in these laboratory tests are usually much less accurate than the THC limits in drug tests. Unfortunately, there are no studies on the effects of HHC on humans, so it's difficult to know with certainty how long HHC stays in the body.
A dose of HHC that takes three days for a 25-year-old's body to process could take a week to get rid of. The user's age, the dose used, and the individual metabolism may affect the time it takes for the body to remove HHC from the system. In preparation for a drug test, the first thing to do is to stop using all cannabis products right away. The safest way to do this would be to buy HHC Isolate, since this would be the purest form of the cannabinoid and would be absent from other cannabinoids. Anecdotal reports are conflicting, with many people claiming that HHC products haven't tested positive for drugs. The fact of the matter is that any minimal amount of THC in your body could cause a drug test to fail.
So, while the odds may be lower by comparison, it is still likely that HHC will cause you to fail a drug test. Therefore, it's a good idea to limit its use if you know you need to get a drug test soon.