Frequency of marijuana use Detection times after use
Single use 3 days
Moderate use, or 4 times per week 5–7 days
Daily use 10–15 days
Heavy use more than 30 days

This table shows how long a urine test can detect certain drugs after a person has taken them:

Drug Detection time after use
Alcohol 7–12 hours
Short-acting barbiturates 24 hours
Amphetamines 48 hours
Heroin 48 hours
Morphine 48–72 hours
Cocaine metabolites 2–4 days
Methadone 3 days
Short-acting benzodiazepines 3 days
PCP 8 days
Long-acting barbiturates 3 weeks
Long-acting benzodiazepines 30 days
How to prepare for a urine test
close up of pharmacists hand selecting medicationShare on Pinterest
It is essential to make the test provider aware of any prescribed medication.

The test requires little preparation. Usually, a person just has to urinate into a plastic container.

It is important to note that certain medicines and supplements can cause false-positive results that indicate illegal drug use.

A person should tell the test provider if they are taking any:

  • prescription medications
  • over-the-counter medicines
  • herbal remedies
  • supplements

A medical professional or technician will carry out the urine drug screen. They may start by asking a person to:

  • empty their pockets
  • remove any excess clothing and items, such as bags and coats
  • clean their hands with antibacterial gel or soap and water
  • clean their genital area with a wipe, which the technician will provide

The technician will then instruct a person to:

  • urinate into a container, until the level of urine reaches a certain point
  • put the lid on the container and return it to the technician

The technician will then measure the temperature of the urine sample to ensure that it is suitable for testing. They will then seal the sample in a plastic bag.

Both the donor and the technician should keep an eye on the sample until it is sealed, to make sure that no one has tampered with it.

Sometimes, the technician will accompany the person into the test room to make sure that they are giving the sample correctly. The technician should explain the reason for this supervision.

Interpreting the results

Urine drug screen results usually come back within a few days. Some results come back on the same day.

Negative results may come back more quickly. A positive result may take longer, because ensuring the accuracy may require further testing.

If a result is positive, a person will need to take a second test for confirmation. This will be a GC-MS test, which will provide more accurate results.

The person who carried out the test or a medical review officer will explain the results.


A urine drug screen can quickly and effectively detect the presence of illegal or prescription drugs in the body.

Doctors, sports officials, and employers may request a urine drug screen for various reasons.

These screens can check for a range of drugs, including marijuana, nicotine, barbiturates, and opioids, such as heroin and methadone. Some drugs remain traceable in the body longer than others.

If an initial result is positive, a person may need to take a second test for confirmation.