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How to Read Urine Drug Test Results

Updated on June 13, 2021

Urine drug test strips are an easy way to detect whether commonly abused drugs are present above the listed cutoff level in someone’s urine. The detection level listed in the instructions tells you how much of the drug being tested is required to trigger a positive test result.

What Does a Faint Line on a Drug Test mean?

A faint line on a drug test is still a line, so if you have a faint line in the Test Region (T) then you have a negative drug screen result.

The intensity of the color of a line on the drug test should not be interpreted as a measure of the amount of drugs present. One of the most common questions we receive is about the faint lines on a drug test and we have confirmed this answer with the manufacturer of the tests - the intensity of the line on a drug test doesn’t mean anything.

The result can only be NEGATIVE or POSITIVE. Any line, no matter how light or dark, in the “T” area of a drug test indicates a negative drug screen result. The possible shades of colored lines in the T Region may vary from person to person.

As you can see in the negative test results photos below, the THC strip is much lighter in color than the OXY test strip, but the test result is still negative.


negative drug test results how to read negative drug test results how to read




Two lines of any color intensity appear to indicate a negative result. A colored line appears in the Control Region (C) and a colored line appears in the Test Region (T). On a multi-panel test, the results area will look slightly different, but in either case you will see a Control Line and a Test Line for each substance being tested.

Even if the line that appears is very faint, the result should be considered negative.

Does a negative drug test result mean I passed?

Yes, a negative result on a drug screening or a laboratory test means the individual “passed” the drug test because the test did not indicate the presence of drugs. However, it doesn’t necessarily mean the level of the drugs being tested is zero.

What does a negative drug screen result mean?

Negative means that the concentrations in the urine sample are below the designated cutoff levels for a particular drug tested. It does not always mean there are absolutely no drugs present in the person being tested, only that drugs are not present above the cut off limit. For example, the cutoff level for marijuana is 50 ng/mL, therefore a person with only 30 ng/mL of THC in their system would test negative on a marijuana drug test.

Drug test cutoff limits, or detection levels, are suggested by SAMHSA in order to prevent too many false positives for traces amounts of a drug in someone's system. Most workplace drug testing programs use a standard set of cutoff levels, however, law enforcement and addiction treatment programs will sometimes use a lower cutoff level in their testing since they have a zero tolerance policy.

If you are using a home drug test, you will want to make sure the cut off level of the test you are using is the same as the one you will be taking elsewhere. Please check your instructions for more information on the cutoff levels being used in your test.


One Line appears in the Control Region (C) and NO line appears in the Test Region (T) to indicate a positive result.

Positive means that the drug concentration in the urine sample is greater than the designated cut-off level for a specific drug and additional confirmatory drug testing may be needed. Please check your instructions for more information on the cut-off levels being used in your test.

What is a preliminary positive drug screen result?

POSITIVE on a urine drug test strip is actually a preliminary positive. A follow-up lab test is required in order to confirm the presence of drugs in a person’s system. A NEGATIVE result rules out the presence of drugs above the cutoff limit, while a POSITIVE indicates there may be drugs present in a higher concentration.

Urine immunoassay drug test strips are easy to use and cost effective to screen for commonly abused drugs without the expense and hassle of frequent laboratory tests. By screening first, only the urine samples that require confirmation need to be sent to the lab for further evaluation.

Will a positive result trigger a follow up lab drug test?

Yes, a urine sample that tests “preliminary positive” must be sent to a lab for evaluation to confirm the presence of drugs. It is possible for a screening test strip to indicate POSITIVE, and a lab to find that an interfering substance other than the drug indicated caused it.

What if I get a false positive drug test result?

Any false positive result will be revealed through a follow-up lab evaluation of the urine sample. There are a small number of substances which could interfere with the drug test strip result, but lab testing of the specimen will clarify the substances which caused the preliminary positive.

How long will drug use show up on a test?

It varies from person to person depending on a wide variety of factors including how frequently it is used, a person’s size and activity level, etc. There is no for-sure amount of time for any drug to show up, however there are estimated windows of probability.

See our Drug Detection Times Chart to get an idea of how long different substances will show up in a drug screen.

What is an INVALID drug test result?

No line appears in the Control Region (C).


what is an invalid drug test result


The most likely reasons for an invalid result are insufficient specimen volume or incorrect procedure. In rare cases it could be the result of a faulty test. Please carefully read the directions again and repeat the test with a new test card. If the result is still invalid, contact us.

How to Read an iCup Drug Test

The Control Region (C) line must appear at the top of each testing window. The results are read for each numbered line below the (C) line and the number corresponds to the drug letters printed below the window. Below are two examples, one with a 13 panel iCup with all negative results and the other showing a positive result for Opiates and Marijuana.


13 panel drug test all negative results 13 panel test positive for opiates marijuana





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