USDTL resource guide
Urine drug panels
Laboratory-based drug testing
A recent-use test with panel options that must match the substances requested in the order.
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
USDTL describes approximately two to three days of history for most drugs. Some substances and patterns of use have longer windows. USDTL offers customized panels and laboratory confirmation of positive results.
What collection involves
Collection requirements depend on the order. Verify the panel, specimen requirements, and any observation or chain-of-custody instructions with the collection site.
Keep in mind
*The short window does not apply equally to every drug. Timing, the substance, and the person all matter.
A common question
Are all drug panels interchangeable?
No. Confirm the exact panel requested by the ordering party. Adding or substituting tests may not satisfy that order.
Read the original resources.
Source material behind this guide.
- USDTL · Urine testingLaboratory urine testing, panel selection, and confirmation.
- 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.