What test strips actually catch — and what they miss

Drug test strips are a real harm reduction tool, but "I tested it" doesn't mean "it's safe." Here's specifically what each strip does and doesn't tell you.

The single most important fact on this page A negative result on any test strip never means a substance is safe. It only means that one specific thing wasn't detected — at concentrations the strip is sensitive enough to catch.
Strip typeDetectsCatches xylazine?Catches medetomidine?
Fentanyl test stripFentanyl and some analogsNoNo
Xylazine test stripXylazine specificallyYesNo
Medetomidine test stripMedetomidine specificallyNoYes
Because naloxone doesn't reverse xylazine or medetomidine on its own (they're not opioids), an overdose involving them can look different — someone may stay sedated even after naloxone is given. Give naloxone anyway if fentanyl might be involved (it usually is, in today's supply) — it can still reverse the opioid component and cost nothing to try. Call 911 regardless.