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Biotech & Biomedical/false positive hair test for alcohol


I am a family physician.I am involved in a custody battle. I have had multiple hair tests for alcohol consumption. I cannot understand how the results can be accurate or even plausable. How could the FAEE be negative and then strongly positive 6 days later on a repeat test. Both tests were carried out at the same lab. Also,I know of another case where a patient had a hair test which was FAEE negative and one month later another test showed a particularly high level for FAEE. At the time of both tests the patient was completely abstinent, but, the second test represented an extra month of sobriety. Please help!Thank you. Mary

Hi, Mary,

Thanks for your question.

I have seen a number of cases of positive hair tests for FAEE in those claiming to be abstinent. It is hard to be certain that these individuals are actually abstinent.

However, if you get a positive results and then a negative result a few days later then this is indicative of a false result and should be repeated.

Single positive FAEE results should not be relied upon as indicative of alcohol abuse.

Analysis of FAEE and EtG in the same sample is a much better indicator.

The reason(s) for the unexpected results in your cases cannot be easily determined.

Hope this helps!

Best wishes,


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Dr.Paul Skett


drug metabolism or biotransformation from basic to advanced, hepatocytes from basic to advanced, drug toxicity and side effects, alcohol clearance and levels


32 years research experience in above areas, 30 years educational experience in University. Retained expert for numerous legal firms dealing with matters of drugs (legal and illegal)and alcohol.

B.Sc(Hons) Biochemistry, University of Liverpool, UK
fil.dr. (Medical Chemistry) Karolinska Institute, Stockholm, Sweden

Fellow of the British Pharmacological Society

Fellow of the Higher Education Academy

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