There is still debate about whether taking zinc supplements will help you pass a urine drug test. It won’t, but adding it directly to your urine will.

The idea of using zinc to beat drug tests has been around for at least 8 years (maybe a lot longer, who knows?). However, based on several message boards, this is still an active area of discussion with continued confusion over whether it is worth trying.

There were a series of studies (here, here, and here) published between 2011 and 2013 that examined whether you can beat a drug test using zinc. They show that zinc can beat a drug test, but only if it is used as an adulterant, meaning that it is added directly to the urine. The evidence that you can take a zinc supplement to pass the test is very weak.

How Zinc Interferes With Drug Tests

I have read some claims that zinc can directly bind THC metabolites in the body and prevent them from going into the urine. For example: “Zinc sulfate is believed to bond with THC metabolites, rendering them too large to filter through the kidneys. In theory, these “bonded” metabolites are then redirected to the feces.” (NORML).

This is flat out wrong. Zinc has never been shown to bind THC and even if it did, it would not prevent it from being filtered by the kidneys. The molecular weight of zinc is only a fraction of THC and it is very well capable of being excreted into the urine.

The reality is that zinc interferes with the drug test itself. As I explain in my drug testing guide, there are two tests run by drug testing labs. The first is a quick and cheap screening test, which uses an immunoassay method. If you fail that one, a confirmatory test is run. This GC-MS test is much more specific and less likely to produce a false positive.

Zinc interferes with the immunoassay test, although presumably it doesn’t interfere with the confirmatory GC-MS test. However, if you pass the immunoassay, they don’t even run the confirmatory test, so this won’t matter.

I won’t go into much detail on how the immunoassay tests work, but they are dependent on an enzyme that produces a colored product. The more THC metabolite present, the less color is produced.

You can see this firsthand with at-home drug testing strips. A colored line means that your urine is negative and no line means that your urine is positive.

Zinc somehow interferes with this reaction, leading to more colored product. The exact mechanism is not understood, but zinc does not significantly change urine pH or directly absorb light (the lab version of the assay measures color based on how much light is absorbed at a specific wavelength).

Because tests for all different drugs use the same basic type of immunoassay, zinc will interfere with all of them. For example zinc has been shown to interfere with tests for cocaine, methamphetamine, alcohol, opiates, barbiturates, benzodiazepines, and PCP.

How Much Zinc Needs to Be Added to Urine?

So knowing that zinc can interfere with a urine test for THC metabolites, the question becomes how much zinc do you need?

The answer: between 1 and 50 mg/mL of zinc sulfate. The three studies varied on how much was needed to see significant interference and this seemed to depend on the levels of the THC metabolite. The higher the level of THC metabolite in the urine, the more zinc was needed to significantly interfere. Generally, 15 mg/mL seems like a good concentration to shoot for.

How much zinc is this? You typically need to provide at least 30 mL of urine for a drug test. This would mean adding 450 mg of zinc to the urine. This is the equivalent of dissolving 2 – 5 zinc pills, depending on the dose.

Can I Take Zinc Supplements?

While it is possible to adulterate your urine by directly adding the zinc after you pee, this is logistically more difficult.  The better alternative would be to take some zinc supplements before your drug test and pee out the zinc. But will this actually work?

After taking zinc supplements, your urine zinc levels do go up significantly. Taking 400 mg of zinc gluconate nearly doubled urine zinc levels. However, the average urine concentration after zinc supplementation was still only 50 ug/dL (0.0005 mg/mL). This concentration is so far below what was needed to cause assay interference, that I would describe this strategy as hopeless.

So why does this continue to be discussed? The original 2011 publication included a small clinical study that led the researchers to the following conclusion: “These results argue that the consumption of zinc supplements taken orally after light marijuana use can interfere with the detection of THC in urine samples for a 12–18-h period.“

This study was shoddy science and I do not agree with conclusions of the authors. The study included only 4 subjects who were given a 200 mg dose of zinc after smoking. Sure, the assay signal went up after taking the zinc, but the reality is that the assay signal was going up and down the whole time anyways. This is normal since how much fluid you consume will significantly affect urine THC metabolite concentrations.

The signal going up after the zinc could just as easily have been a coincidence. In combination with the other study showing that you need much higher urine zinc levels to interfere with the assay, I do not believe that zinc supplements help.

Can Zinc Be Detected in Urine?

Yes, the 2013 study shows that high zinc levels can be detected in your urine with a relatively simple test. However, as far as I know, no testing labs have incorporated zinc testing into their routine adulterant tests.

Conclusions on Using Zinc to Beat a Drug Test

I don’t believe that taking zinc supplements will do anything to beat a drug test. Your urine zinc levels simply won’t be anywhere near high enough to interfere with the test. However, you are always free to buy zinc supplements and find out yourself.

The only way that zinc is helpful is if you add it directly to your urine, which carries its own set of risks.