If you have been asking yourself, "Does CBD show up in a drug test?" the answer is simple—no. That’s irrespective of the preparation and/or dosage. This we have on the authority of U.S. Drug Test Centers, an affiliate of the U.S. government's Substance Abuse and Mental Health Services Administration, or SAMHSA. 
However, this doesn't mean you can sit back and relax about drug tests just yet, so read on for:
RELATED: Does CBD Show Up on Drug Tests?
Well, the answer is, again, very simple—CBD or cannabidiol doesn't show up because there are no tests designed to detect it specifically in the body. And why would there be?
The U.S. Drug Enforcement Administration (DEA) recently clarified their position on CBD and the Controlled Substances Act, which prohibits the possession of marijuana. In this brief, they state that cannabidiol is, by law, not considered an illegal substance. They're targeting tetrahydrocannabinol, or THC, which is the psychotropic agent in marijuana. 
THC is also the reason you need to take care when tests are conducted, but more on that later.
The current drug tests, usually using samples of saliva or urine, are designed to pick up a specific metabolite associated with THC. 
In an interview with U.S. Drug Test Centers, Quest Diagnostics Director of Science and Technology Barry Sample said: “If the product contains only CBD and has had the THC removed, then an individual being tested would not be expected to test positive for marijuana or marijuana metabolite.”
Apparently, the recommended cutoff level of THC is 50 ng/mL to pass a drug test, according to SAMHSA. U.S. Drug Test Centers also point out that "most employers and legal services prefer to use SAMHSA-certified labs as the standard since it’s more likely to hold up in court. Most hemp oil or CBD products are usually sold with much lower levels of THC (compared to marijuana), so most CBD consumers won’t have trouble passing a drug test."
CBD is, in fact, pretty blameless, as illustrated in a 2011 review of the literature. Here it explains that CBD is safe, well tolerated, and not a mind-altering substance:
"Several studies suggest that CBD is non-toxic in non-transformed cells and does not induce changes on food intake, does not induce catalepsy, does not affect physiological parameters (heart rate, blood pressure, and body temperature), does not affect gastrointestinal transit and does not alter psychomotor or psychological functions. Also, chronic use and high doses up to 1,500 mg/day of CBD are reportedly well tolerated in humans." 
What's more—CBD is legal in almost all 50 states, so provided that you qualify for legal possession where you live, you shouldn't have a problem with possession or testing. Just make sure that the state law provides protection for work if yours subjects you to any drug tests.
Yes, a study was done in 2007 that indicated the possibility of CBD converting to THC, but these were lab and animal tests. So, there's currently no clinical evidence that CBD significantly converts to THC in the body.
Also, the authors concluded that the converted cannabinoids show "Δ9-THC-like effects in mice, although their pharmacological effects were less potent than those of Δ9-THC." This means that even if CBD does convert, this study suggests that the THC effects are not the same.
Furthermore, there is no evidence that CBD has caused a false positive drug test for anyone—ever. What you need to look out for is the THC content of any CBD product you use. There is likely to be some, as the two cannabinoids are known to work best together. Yet it is usually only trace amounts that will not test positive in a drug test.
If you are a regular marijuana user or the CBD oil you vape with contains more than 0.3mg of THC, you will need to take steps to avoid a positive drug test.
Don't use marijuana or CBD products with high THC content if your work prohibits this and subjects you to random testing. There is no way you can avoid a positive test on short notice.
The above applies, but there's good news if you're vaping CBD oil. It has a number of putative advantages over smoking a joint, apart from avoiding the heady effects of THC-heavy cannabis or related products.
Note that the following only applies if you're using a high-quality, CO2-extracted CBD vape juice.
So, the question "Does CBD vape oil show up on a drug test?" should be well answered. If you suffer from any chronic lung condition, first consult with your physician before vaping with CBD.