Faint Line on Drug Test: Meaning and Causes

The kit employed for urine drug test is reliable yet a cheaper way of screening the drug abuse. Every drug test involves a predetermined detection level which can tell if a drug test is positive or negative. However, it’s important to note that these tests do not give any information regarding the amount of drug present within the body. At times, people get a faint lineon drug test which may be due to several possible reasons that will be further discussed here.

What Does Faint Line on Drug Test Mean?

When reading the drug test result, you will find a line at the very top of every testing window and that is the control region (C). The test is not considered valid without this line. Result is considered negative when a colored line appears in both the control (C) and test (T) region. If the colored line appears in the control region but not in the test region, the test is considered to be positive. Nevertheless, presence of any faint line in the test region (T) will indicate negative results no matter how light it is.

The color intensity of the line in a drug test result must not be confused with the quantity of drug present in the body. A positive urine drug test requires presence of minimum drug quantity in the urine specimen. In case of some drugs, the minimum drug quantity is rather high such as amphetamines (1000ng/ml) whereas it’s low in other drugs such as marijuana (50ng/ml). If the minimum amount is low, there will be a faint line on drug test.

Possible Causes of Faint Line on Drug Test

1. Composition of Urine May Interfere with the Results

The urine composition differs slightly for each individual mainly because of the medication intake, fluid consumption and overall health. The urine test result of the donor may exhibit faint lines within the time limit on some immunoassays. The test results will be considered negative of course.

2. Some Medications May Produce the Same Effect

Some OTC drugs are chemically similar to the drugs that are screened in the rapid drug test. Due to the similar compound as that present in the drug being tested, the faint line might appear in the test region (T) or may even lead to false positive result. This is one of the main reasons why counter checking with other techniques is often necessary.

3. Every Testing Product Is Different

When performing a drug test, screening for multiple drugs, up to twelve, may be done simultaneously. As a result of this, it becomes difficult to remember each assay as an individual diagnostic test like some drugs may exhibit a lighter line.Due to this assays of tricyclic, antidepressants and benzodiazepines may also get affected.

4. There Is Remaining Drug in the Urine

At times, faint line on drug test maybe due to the presence of a little quantity of drug remaining in the urine sample especially in TCH screening test. If the drug concentration is below the cut-off level, the result will be considered negative.

Common Questions About Drug Test

1. My child confessed he used drugs a week backHowever, the test result was negative. Why?

Some drugs take a few days to eliminate from the body, except marijuana when used chronically. If your child isn’t a chronic smoker, chances are the drug eliminated from his bodybefore the test.

2. Can I get a positive TCH result because of secondary smoke?

According to the studies, some amount of drug does get inside the body due to exposure to secondary smoke of marijuana.However, it’s not enough to give positive screening result.

3. Can urine be scooped out of the toilet for drug screening test?

A big fat no! Toilet urine may become diluted and has a chance of exposure to cleaning agents that may alter the result.

4. If I drink plenty of water, will it affect my result of the urine test?

Water may dilute the urine specimen. It only works if you are really close to the cut-off level. Dilution is also considered to be a cause of faint line on drug test.

5. When can I be able to read my results?

If the test is valid, the line will appear in the colored region. The appearance of line in the test region will indicate negative results whereas no line will appear if the result is positive. You must wait for at least five minutes.

6. What should I do in case of positive results?

Positive results are further confirmed for the identification of the drug used via gas and liquid chromatography or mass spectrometry, but that’s rather an expensive procedure.

7. How to avoid false drug test results?

Try following the instruction when doing the drug testing. The urine must be fresh and undiluted, dipped up for 10 seconds at least. At times, false results are a consequence of saturation. It’s advised to test every panel equally for 10 seconds before rushing for the results. 

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