Ensuring a Clean Sample

Ensuring a Clean Sample

First Check® Home Drug Tests are highly accurate in detecting drug use. But they can only work effectively when steps have not been taken to avoid a positive test result.

Below are tips to help ensure a clean sample, plus four of the most common methods used to avoid positive detection:

Testing Tips

  • On the day of the test, wake your child in the morning, let them know you will be testing them for drugs and escort him/her directly into the bathroom.

  • Use first morning urine, as it is typically the most concentrated and best for detecting the presence of drugs.

  • Stay in the bathroom and supervise urine collection-start to finish.

  • Have your child hand you the urine-filled cup immediately after collection. It should be warm to the touch.

  • Don't leave the sample unattended until you have the final test result and are sure you won't be sending it to the lab for confirmatory testing.

Common Ways of Avoiding a Positive Result


  • If a tester drinks large amounts of water (at least one gallon) before taking a drug test, urine becomes diluted and metabolites from drugs may become undetectable.

  • This may cause the first round of results to be inconclusive. If a second test is necessary, more time will have passed and detectable quantities of drugs may have naturally passed through the system.

  • Another method of dilution is adding a drop of water to the sample. Whether ingested or added to a sample, water can make urine look extremely pale and raise red flags indicating that the sample has been tampered with.

Cleansing Products

  • There are an increasing number of products sold that claim to “cleanse the body of toxins” and specifically claim to mask illicit drugs in the system.

  • These formulated “detox” drinks are sold at local nutritional supplement stores and are widely available online.

  • They contain ingredients such as filtered water, fructose, maltodextrin, citric acid, potassium citrate, potassium benzoate, ascorbic acid, red 40, riboflavin, and more.

  • They work by masking the drug metabolites found in the urine. There is often a limited amount of time that these products can effectively conceal drug use (i.e., 3 to 4 hours).

Chemical Adulterants

  • Some of the most common agents that are added to a urine sample include bleach, eyedrops, hand soap, vinegar, table salt, and lemon juice.

  • These chemicals can be easily concealed in small vials and are usually added to the sample when individuals are taking the test unsupervised.

Synthetic Urine

  • Another common method for concealing drug use is to substitute “clean” urine that does not have any trace of illicit drugs.

  • This can be accomplished by asking a friend for a clean sample or by purchasing a clean sample online. (The clean urine is usually refrigerated, and the temperature is a clear sign that the sample is not valid.)

Let's Talk About Drugs

Get helpful tips for starting the conversation about drug abuse with your loved one.