A clearer comparison.

See the specimen, purpose, and general time frame side by side. Testing windows are estimates, not guarantees.

Different tests look back different amounts of time.

Compare general windows, then open a test to understand its limits.

Test / specimenGeneral window

Hair drugsScalp hair~90 days PEthBlood~2–4 weeks Urine EtG / EtSUrine~1–3 days Urine drugsUrine~2–3 days*Hair EtGScalp hair~90 days

Days of history before collection

CDT works differently. It reflects a sustained-use pattern, so it is not plotted as a fixed detection window.

Approximate windows, not guaranteed detection or clearance. Bars show general span, not continuous coverage or a probability. Three months is shown as 90 days. PEth can persist six weeks or longer in isolated cases; urine varies by substance and use. View sources.

Build an interactive test comparison

The details, side by side.

Comparison of six court testing guides
Test	Focus	Specimen	General window / context	Source
Hair drug testing	Drugs	Scalp hair	Up to ~3 months	USDTL
PEth blood testing	Alcohol	Dried blood spot or whole blood	Up to ~2–4 weeks	USDTL
CDT blood testing	Alcohol	Serum from a blood draw	Pattern of sustained use	Quest Diagnostics
Urine EtG / EtS	Alcohol	Urine	Approximately 1–3 days	USDTL
Urine drug panels	Drugs	Urine	Usually ~2–3 days*	USDTL
Hair EtG testing	Alcohol	Scalp hair	Up to ~3 months	USDTL

Windows vary with the substance, specimen, analytical cutoff, and pattern of use. A longer window does not make a test universally better. Confirm the order before choosing.

One test may not answer every question.

Urine, blood, and hair offer different views. Panel contents matter just as much as the specimen. Your ordering party determines which test or combination is appropriate.

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