Masking is another possible way of beating a drug test that is completely legal. This strategy involves ingesting a particular substance that disguises (or masks) the traces of drug metabolites in the urine sample which means that they can't be detected by drug testing.

Word on the street claims that there are several products that can remove drug traces from urine, however some of these are questionable when it comes to actually producing results. Some products that are frequently mentioned include vinegar, aspirin, cranberry juice and goldenseal. There is also the commercially available tea called U-R-KLEAN. These are cleansing kits that are supposed to produce clean urine. A recent study into 50 different herbal teas found that there was little evidence that they mask drug traces in urine. The only impact that teas have on the results of drug testing is probably due to the fact that the person is drinking more liquids and therefore flushing their system.

In his book "Ur-Ine Trouble", Holtorf contends that the fact that goldenseal contains hudrastine and berberine means that the THC concentration in urine samples is decreased only if the user has taken a high dosage. The issue with this is that the user would need to take so much goldenseal that it would be impossible to be so orally. There is no other way to ingest enough goldenseal to have an impact on altering the concentration of THC in a urine sample.

Vitamin C

Schwarzhoff and Cody (two drug researchers) found that consuming vitamin C can lead to a false negative when tested for amphetamines, marijuana or barbiturates. According to Holtorf, taking between 8,000mg and 10,000 mg of vitamin C in the 4-6 hours before being drug tested and then having more only 2 hours before the test may be effective in masking signs of marijuana usage.

Vitamin C, in large doses, can be an effective because it increases the acidity of urine and this increases the excretion of cocaine, phencyclidine and amphetamines. Some people have relied on this information to develop the strategy of taking vitamin C in the 2 or 3 days leading up to the drug test so that they have an increased chance of eliminating traces of drug use.

Using vitamin C as a masking agent can be tricky because if it is taken directly before a test by someone who has been using cocaine, phencyclidine or amphetamines, the fact that it increases the excretion of these chemicals may actually mean that the traces of these drugs in the urine sample are higher, which increase the chance of a positive test result.

Other Masks

Bicarbonate and some antacids (such as Rolaids and Tums) slow the excretion rates for PCP, cocaine and amphetamines which can reduce the chance of a positive test result. Tolmetin, which is a prescription nonsteroidal anti-inflammatory) is also a popular masking agent. Dr Cone's research team reported that there are some agents that work to mask opioids and cannabinoids in urine samples. Ciprofloxicin, a regularly prescribed antibiotic, can mask amphetamines, cocaine, opiates and benzodiazepines in tests using the immunoassay methods.