Urine drug testing, also known as a pee drug test, is a common way to screen for illegal drugs and prescription medications. Drug tests analyze a sample of urine to detect specific drugs and their metabolites, which are the byproducts of drugs after they have been processed by the body. There are a few key things that pee drug tests screen for:
Common illegal drugs
The most common illegal drugs that standard pee drug tests look for include:
| Cocaine | Heroin |
| Marijuana | Methamphetamine |
| Phencyclidine (PCP) | Lysergic acid diethylamide (LSD) |
Cocaine can be detected in urine for up to 3 days after last use. Heroin is detectable for 1-2 days. Marijuana is highly variable, but can be detected for 7 days for occasional users and for 30+ days for heavy users. Methamphetamine can be found for 1-3 days. PCP is detectable for 7-14 days and LSD for just 1-3 days.
Common prescription drugs
Pee drug tests also commonly look for the following types of prescription medications that are frequently misused:
| Opioid painkillers like codeine, morphine, and oxycodone |
| Benzodiazepines like alprazolam, diazepam, and lorazepam |
| Barbiturates |
| Amphetamines |
Opioid pain medications are detectable in urine for 1-4 days depending on the specific drug. Benzodiazepines can be found in pee for up to 7 days. Barbiturates are detectable for up to 6 weeks, and amphetamines for 1-3 days.
How drug tests analyze urine
When collecting a urine sample for drug testing, the urine is first screened using an immunoassay test. This test detects levels of a particular drug above a set concentration cutoff. If the concentration is above the cutoff, the sample is flagged as potentially positive.
All presumptive positive samples then undergo confirmatory testing using a more precise method like gas chromatography/mass spectrometry (GC/MS). This second test specifically identifies if the flagged drug or metabolites are indeed present in the sample. Only if the GC/MS test is positive will the final result be reported as positive.
Standard 5-panel drug tests
The most common type of pee drug test is the standard 5-panel test. This tests for:
| Marijuana (THC) |
| Cocaine |
| Amphetamines |
| Opioids |
| Phencyclidine (PCP) |
The 5-panel test detects a wide range of drugs, but still misses some commonly abused substances like benzodiazepines, barbiturates, and methadone.
Expanded drug tests
Expanded urine drug tests look for the 5 standard drugs plus a wider range of additional substances. For example, a common expanded test is the 10-panel drug test. This covers all the drugs in the 5-panel test plus:
| Methadone |
| Propoxyphene |
| Benzodiazepines |
| Barbiturates |
| Methamphetamine |
Even more comprehensive testing can look for up to 26 different common drugs. This more extensive screening helps detect a wider range of misused prescription medications and illegal substances.
Detection windows for common drugs
The detection window for drugs in urine can vary widely based on the chemical, dose, frequency of use, metabolic rate, body mass, age, overall health, and urine concentration. Here are some general detection window estimates:
Marijuana
| Casual use: | 3-7 days |
| Chronic heavy use: | 15-30 days; up to 45-90 days for regular heavy users |
Cocaine
| Casual use: | 1-3 days |
| Chronic heavy use: | 5-7 days |
Methamphetamine
| Casual use: | 1-3 days |
| Chronic heavy use: | 5-7 days |
Opioids
| Codeine: | 1-2 days |
| Morphine: | 1-3 days |
| Oxycodone: | 1-4 days |
| Methadone: | 3-8 days |
Benzodiazepines
| Short-acting (Xanax): | 3 days |
| Long-acting (Valium): | Up to 30 days |
Barbiturates
| Short-acting (pentobarbital): | 2-3 days |
| Intermediate-acting (amobarbital): | 2 weeks |
| Long-acting (phenobarbital): | 2-6 weeks |
Amphetamines
| Casual use: | 1-2 days |
| Chronic heavy use: | Up to 7 days |
These windows can vary considerably based on individual factors and dosage. Additionally, hair follicle testing can detect most drugs for much longer, typically around 90 days.
Cutoffs for positive results
Each drug test has a cutoff level for what concentration of a substance will trigger a positive result. Even if a drug is present in the urine sample, it must meet or exceed the cutoff to be reported as positive. Here are some common cutoff levels:
5-panel drug test cutoffs
| Marijuana metabolite THC: | 50 ng/mL |
| Cocaine metabolite benzoylecgonine: | 150 ng/mL |
| Amphetamine: | 500 ng/mL |
| Methamphetamine: | 500 ng/mL |
| Opioid metabolite: | 2000 ng/mL |
| Phencyclidine: | 25 ng/mL |
10-panel and extended drug test cutoffs
Additional cutoffs on expanded tests may include:
| Benzodiazepines: | 200 ng/mL |
| Barbiturates: | 200 ng/mL |
| Methadone: | 300 ng/mL |
| Propoxyphene: | 300 ng/mL |
| Ecstasy (MDMA): | 500 ng/mL |
Types of drug tests
There are a few different methods urine drug tests use to analyze samples:
Immunoassay or EMIT
Immunoassay tests use antibodies that attach to specific drug metabolites in the urine. Compounds like enzymes or radioisotopes are also used to allow for detection. This method is relatively fast and cost-effective, so it’s utilized for initial screening tests. However, immunoassays can sometimes cross-react and detect related compounds, leading to false positive results in some cases.
GC/MS
Gas chromatography/mass spectrometry (GC/MS) separates and identifies precise molecular compounds within a urine sample using a combination of gas chromatography and mass spectrometry. While more expensive and time-consuming, GC/MS is considered the gold standard for confirmation testing to rule out false positives and conclusively identify specific drugs and metabolites.
LC/MS/MS
Liquid chromatography/tandem mass spectrometry (LC/MS/MS) is an alternative precise testing method sometimes used instead of GC/MS for confirmation testing. It uses liquid chromatography and two stages of mass spectrometry to separate and identify drug compounds.
Dip tests
Dip or instant tests provide very fast on-the-spot screening results, usually within 5-10 minutes. The sample is applied to a testing strip coated with drug antibodies to allow for preliminary detection. These tests are inexpensive and convenient, but not as sensitive as lab-based immunoassays. Positive dip stick results still require laboratory GC/MS confirmation.
Urine, blood, hair, and saliva drug testing
Urine is the most widely used specimen for drug testing, but compounds can also be detected through analysis of blood, hair, and saliva samples:
Urine testing
Urine drug tests are most common because they are:
– Non-invasive to collect
– Unable to be adulterated or tampered with during monitored collection
– Detect recent drug use during the detection window
– Have established cutoff levels for positive detection
– Low cost compared to blood or hair testing
Blood testing
Blood tests can detect recent very heavy marijuana use or hallucinogen use not caught by urine tests. Blood samples can determine if drugs were used within the past day or two. However, collection is more invasive and samples can’t be re-tested.
Hair follicle testing
Hair drug tests measure drug metabolites incorporated into the hair shaft. Head hair can detect substance use over approximately the past 90 days, even for infrequent drug use. Pubic hair can detect drug use over approximately the past month. Hair testing is more difficult to tamper with and has a longer detection window, but is more expensive than urine testing.
Saliva testing
Saliva drug tests detect drug use during approximately the past few days. They are less invasive than blood and urine tests. However, saliva testing is not yet as accurate or established for drug test detection cutoffs and collection is more easily tampered with.
Masking drugs in urine
Those undergoing drug testing may attempt to use various methods to try to mask or alter the test results. Common ways people try to beat urine drug tests include:
Dilution
Drinking excessive amounts of water can dilute urine and bring drug concentrations below the cutoff levels. Tests often measure creatinine levels to check for dilution, but creatine supplements can sometimes be used to increase creatinine back to normal levels.
Substitution
Urine substitution involves using drug-free urine from someone else or synthetic or fake urine rather than your own specimen. Labs check samples for pH, specific gravity, creatinine, and other markers to detect substitution.
Adulterants
Adding adulterants to urine samples aims to interfere with drug detection, for example by changing pH or destroying metabolites. Bleach, vinegar, drain cleaner, eye drops, salt, or even aspirin are sometimes used. Many labs now screen for known adulterants and adulterated samples may be rejected.
Detoxification
Detox drinks, teas, pills or other products claim to flush out drug metabolites by speeding up urination, diluting urine, or interfering with detection. There is limited evidence they are effective, especially for heavy drug use. Any effect is temporary.
Cheating & falsifying urine tests
Providing a false sample carries serious risks and consequences if caught. However, some still attempt methods such as:
Synthetic urine
Premixed synthetic urine substitutes are designed to imitate the composition, ingredients, color, specific gravity, pH and other qualities of natural human urine to try to cheat drug tests. These products are illegal in some U.S. states. Labs often detect their use.
Urine additives
Some try to spike their own diluted urine with compounds like uric acid or potassium nitrate to mimic normal creatinine levels and specific gravity. This aims to hide dilution. Labs often test for these adulterants.
Fake penis & bags
Using a prosthetic urine device allows another person’s clean urine to be smuggled into a test and substituted in place of your own sample. However, labs often carefully monitor collection to detect such attempts.
Conclusions
In summary, standard urine drug tests detect illegal substances like marijuana, cocaine, and amphetamines as well as commonly abused prescription drugs such as opioid painkillers and benzodiazepines. Expanded 10-panel tests add in methadone, barbiturates, and other drugs. The most precise confirmation testing uses GC/MS or LC/MS/MS to identify specific drug metabolites. Detection windows vary widely based on the drug, dosage, frequency of use, and individual metabolism and excretion. While it is possible to tamper with specimens, cheat, or try to mask drug use, this carries significant risks if caught. The most reliable results come from carefully monitored urine drug tests analyzed by reputable accredited laboratories using proper collection procedures, strict chain of custody protocols, initial immunoassay screening, and GC/MS confirmation of presumptive positive results.