The best strategy for preparing for a drug test is abstinence. Simply put, this involves not taking any drugs at all, including illegal drugs, legal drugs and over-the-counter medications which may produce a positive test result.

This strategy is not perfect as you may still get a false positive when you haven't taken any drugs at all. This could result from a mistake at the lab, a particular food you've consumed, or something in your biology causing a positive result. A false positive raises suspicion about you and means that you need to undergo further testing. This can be quite stressful due to the potential impact it has on your profession and reputation.

Avoid Medications

Using a legal, over-the-counter medication for a cold or flu may cause a positive result for a drug test that is testing for opiates or speed. This is known as a false positive because the test is positive even though you haven't taken an illicit drug. The government knows that this happens and they have developed a testing process that is supposed to properly deal with it. This process involves allowing you to provide information about the legal medications that you've used before the test and then discussing this with the MRO if your test is positive. If the MRO accepts your explanation for the positive result, he or she can change it to negative without informing your employer.

Still, it's much better to avoid this suspicion and stress by not getting the false positive result in the first place. A good way of avoiding this risk is by not taking certain medications that are likely to cause false positive results. These medications include:

  • Alka-Seltzer Plus
  • Alleres
  • Bronkaid
  • Contac
  • Donnagel
  • Nyquil
  • Primatene
  • Sinutab
  • Sudafed
  • Triaminic
  • Detection Times

If you are planning on abstaining from drugs as your way to pass drug tests, then you need to ensure that you refrain from taking drugs for enough time for the metabolites to disappear entirely from your system. The time that a metabolite remains in your bodily fluids is referred to as the "detection period". The detection period will vary significantly for different drugs, due to their different chemical compositions. It will also depend on the individual's drug taking history, age, sex, weight and overall health. The detection period for cocaine, for example, is quite short (12-48 hours) while for marijuana it is much longer and dependant on the user's history. If a person uses marijuana casually, the detection period is around 2-7 days. If they use marijuana chronically, then the detection period can be up to 2 months. Having just one puff on a weak joint will usually only be detectable for around 12 hours.

The abstinence period required to produce a negative result varies because drugs metabolize and are excreted at different rates. The table below demonstrates the different detection periods for various drugs. This table was originally developed by PharmaChem, a drug testing company located in Menlo Park in California.

Drug Detection Periods in Urine

Drug Detection Period
Amphetamines - Stimulants
Amphetamine Up to 72 hours
Methamphetamine Up to 72 hours
Barbiturates - Sedative Hypnotics 1-4 days
Amobarbital 2-4 days
Butalbital 2-4 days
Pentobarbital 2-4 days
Phenobarbital Up to 30 days
Secobartial 2-4 days
Bensodiazepines - Sedative Hypnotics
Diazepam (Valium) Up to 30 days
Chlordiazepoxide (Librium) Up to 30 days
Cannabinoids - Euphoriants
Marijuana Casual Use 1-4 days
Marijuana Chronic Use Up to 14 days
Cocaine - Stimulants
Benzoylecgorine Up to 72 hours
Ethanol - Sedative Hypnotics
Alcohol Very short
Methadone - Narcotic Analgesics 1-4 days
Methaqualone - Sedative Hypnotics
Quaalude 2-4 days
Opiates - Narcotic Analgesic
Codine 2-4 days
Hydromorphone 2-4 days
Morphine for heroin 2-4 days
Phencyclidine (PCP) - Hallucinogens
Casual Use Up to 5 days
Chronic Use Up to 14 days

Individual Differences

The drug detection periods also vary significantly for different people. The factors that influence how long the drug metabolites will stay in your system include such things as weight, metabolism speed, fat level, how long you have been using drugs, how often you use drugs and the dosage that you consume. Dr John Morgan, a Medical Professor and the Director of the Pharmacology Program at New York's City University says that an individual who smoked marijuana chronically before being incarcerated retained the acid metabolite in his system for over 2 months. According to PharmaCare, positive test results for marijuana following an abstinence period of 1 month is very rate. This is something that regular marijuana smokers should be aware of. Even though this is a relatively benign drug that is often viewed as safer that tobacco and other drugs, it is very easy to detect marijuana use. Also unfairly, this is also the hardest drug test to beat.

Sensitivity Testing

The detection period will also depend on the sensitivity level of the drug test that is being used. There are two different cutoff sensitivities that can be used with the EMIT tests: high and low. The high cutoff is about 5 times more than the low level. Being aware of the test's sensitivity level will allow you to prepare for the required abstinence period. The general rule to observe is if you have any doubts, abstain! In some cases people will take a sick day on the day of the test so they have an extra day to abstain, but this move may actually create suspicion.