What Do Faint Lines Mean on a Drug Test? 6 Possible Reasons Why.

Although a faint line indicates that the urine sample is negative (clean) for the drug being tested, there are some factors that can lead to the line being faint: 

1. Insufficient Testing Time 

    A faint line may occur if the strip is not left in the urine sample for the recommended time. Ideally, the strip should be dipped into the specimen for approximately 30 seconds or until the C (control) line appears. 

    2. Low Detection Level 

    The fainter the line is, the lower the cutoff threshold. As such, a kit with a low detection level (THC 15 ng/mL, COC 150 ng/mL) will most likely show a faint line at the T (test) line. 

    For example, the THC 15 ng/mL detection is at a much lower level than the cut off for Methamphetamine at 1000 ng/mL. Therefore, in the case of a negative (clean) test result, the T line will be darker on a Methamphetamine test than the THC 15 ng/mL test. 

    3. Low Presence of a Drug Below the Detection Level 

    There is not enough presence of a drug in the system to trigger a positive result. However there still may be a small trace in the urine sample; causing a faint line. 

    4. Diluted Urine 

    Diluting the urine may come in the form of adding water to the urine sample itself or if an individual drinks an abnormal amount of water before testing. It is recommended to use the first urine sample of the day for the most accurate test results. 

    5. Use of Detox Agents 

    Detoxes/cleansing agents will likely cause a faint line next to the T. This is due to the urine being diluted or because the test result is false negative (clean). The masking products cause frequent urination, which flushes the drug out of the person’s system. 

    6. Use of CBD or Delta Products 

    As mentioned previously in the article, the presence of THC below the test detection level can cause a faint T line on a drug test. Since CBD, Delta products or other synthetic/THC alternatives have low amounts of the drug in them, they may cause an individual to have THC in their system below the ng/mL testing level, causing a faint T line. 


    How to Get Accurate Drug Test Results 

    Although a faint line on a drug test indicates a negative (clean) test result, it may not be accurate if detox/masking agents or a diluted urine sample was used prior to testing.
    To get the most accurate results on your test, make sure to: 

    • Notify your doctor of any medications that may interfere with drug test results.
    • Collect the urine sample first thing in the morning, prior to consuming liquids.
    • Use a kit that utilizes lab-standard immunoassay methodology. 
    • Use adulteration strips that detect the presence of masking agents. 
    • Read the results 5-30 minutes after usage. 
    • Avoid using expired drug test kits. 
    • Store the test kit at room-temperature. 
    • Avoid using any low level THC products (CBD/Delta) for a few days prior to testing. 
    • Abstain drinking a high volume of liquid(s).


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