Drug Testing BLOG

Faint lines on drug tests are very common no matter what method of screening is being used. It's crucial to understand how to interpret drug test results, including faint lines, in order to make confident decisions and prevent liability claims for inaccurate results.

What does a faint line on a drug test mean?

If a faint line appears in the Test Region of a drug test, this still counts as a NEGATIVE TEST RESULT. Drug test results do not vary based on the intensity of the colored lines. This means that even if the line is very faint, the test has not found any trace of that specific substance.

What does a negative drug test mean?

A negative drug test does not necessarily mean the donor has never used any of the substances being screened. If a preliminary drug test result is negative, this could mean that drug metabolites in the donor's system did not meet or exceed the cutoff concentration levels established by SAMHSA. In order for a test result to be positive, a certain quantity of metabolites is required to react with the built-in test strip reagents.

How accurate are at home drug tests?

Most home drug tests are FDA Approved to perform just as well as corporate drug testsA very faint line on a home drug test is indicative of a negative test result, as mentioned above. 

How to read drug test results

Instant drug tests are designed for easy interpretation. Both integrated urine test cups and saliva drug tests contain built-in strips that react to drug metabolites present in a donor's sample. Each test strip features a Control line, to indicate the test is functioning properly; and a Test line, which will only appear if drugs have NOT been found for a particular substance. For further assistance, learn how to read a drug test cup.

Related Resources

CRC Health Drug Test Accuracy

U.S. Department of Labor

DOT Substance Abuse Professionals (SAP)