Will hair drug testing leave bald spots?

By John Hawes | Last updated: August 23, 2018

No, drug testing will not leave bald spots. When hair is taken for drug testing, the follicle or root is not taken for sampling nor is your head shaved. You may have small spots where your hair has been cut very short but the collection process will not leave bald spots.

To obtain an adequate sample for drug testing, a collector will cut between 90 to 120 strands of hair from your head. Each .5 inch length of your hair represents approximately 1 month of hair growth. The preferred minimum length of each strand obtained for testing is 1.5 inches. This length of hair permits the testing lab to detect potential drug use over a 3-month period. Because the hair closest to your scalp will reflect your most recent drug activity, the hair sample is cut from as close as possible to your skin without damaging the follicle or root.

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Hair samples may be taken from other parts of your body instead of the head, such as your chest or arm pit, but these samples do not provide an accurate indication of the time frame of any drug use. Therefore, if your head hair is too short to provide an adequate sample size, it is likely that an alternative drug testing method will be used.

Since only a small amount of hair is required for drug testing, the collector will probably be able to take segments from the base of your head or other areas that are inconspicuous. Your remaining hair should cover the places where the sampling cuts were made.

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Written by John Hawes

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John Hawes is the CCO and co-founder at SureHire Occupational Health Testing. John graduated in 2001 from the University of Alberta with a Bachelor of Science degree in physical therapy. As a former physical therapist, John uses his knowledge of physical therapy and interest in ergonomics and biomechanics to devise fit for work testing.

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