USDTL resource guide
Hair EtG testing
Alcohol testing in scalp hair
A longer-term alcohol biomarker measured in hair, separate from a hair drug panel.
The approximate testing window
A visual reference for this specimen.
Approximate window, not guaranteed detection or clearance. The bar shows a general span, not continuous coverage or a probability. Shaded ends represent the stated range. Review the limitations and sources below. View sources.
What this test tells you
EtG in scalp hair can provide a view of alcohol exposure over approximately three months. The sample and analytical method determine how the result should be interpreted.
What collection involves
Confirm that the order specifically requests hair EtG. The collector will assess sample length and the amount needed for the ordered tests.
Keep in mind
Hair EtG is not a record of individual drinking events. Discuss cosmetic treatment and specimen limitations with the reviewer.
A common question
Can hair treatment change the result?
Yes. USDTL describes reduced hair EtG from certain cosmetic treatments, which needs to be considered when interpreting results.
Read the original resources.
Source material behind this guide.
- USDTL · The long gameHair EtG and the effect of cosmetic hair treatments.
- USDTL · Hair drug testingScalp hair, specimen collection, and the approximate three-month window.
- USDTL · Reservoir matrices (PDF)Why specimen results cannot establish an exact dose or time of use.
Reviewed October 26, 2026. Laboratory guidance can change; the current order and report take priority.