Fentanyl Adulterant Tracker
What is actually being mixed into the US fentanyl supply, in plain numbers. Every figure below comes from the DEA’s NFLIS forensic-laboratory system, the CDC, or peer-reviewed research — with the source named and dated. Free to cite; please link back.
The 2025 numbers
NFLIS-Drug recorded 1,126,178 substance identifications across 666,357 cases in 2025. These are the substances most often found alongside fentanyl — the adulterants and co-reports that define the modern supply:
| Substance | 2025 NFLIS reports | Rank | What it is | Why it matters | Naloxone? | |
|---|---|---|---|---|---|---|
| Xylazine (“tranq”) | 18,138 | #6 | Veterinary sedative | Necrotic skin wounds, hours-long blackouts, blood-pressure crashes | No — but give it anyway: fentanyl is almost always present too | Profile → |
| Medetomidine (“rhino tranq”) | 8,980 | #10 | Veterinary sedative, 100–200× xylazine’s potency | ICU-grade withdrawal, profound sedation, dangerously slow heart rate | No — same fentanyl caveat | Profile → |
| BTMPS (Tinuvin 770) | 8,138 | #11 | Industrial plastic UV stabilizer | Calcium-channel blocker, no antidote; the “bug spray” smell tell | No — no antidote exists | Profile → |
| para-Fluorofentanyl | 3,535 6,708 all isomers | #16 | Fentanyl analogue | Full opioid overdose risk; routinely co-detected with the adulterants above | Yes — naloxone works | Profile → |
| Heroin | 27,286 | #5 | Classic opioid | Still co-reported with fentanyl in thousands of exhibits | Yes | Profile → |
| Cocaine & methamphetamine | 195,317 / 323,404 | #2 / #1 | Stimulants | Not adulterants of fentanyl — but ~1 in 4 cocaine and ~1 in 8 meth exhibits now test positive for it | Yes | Profile → |
The story of 2025–26: medetomidine’s takeover
- Medetomidine NFLIS reports: 247 (2023) → 2,616 (2024) → 8,233+ (2025) — a 950% jump, then another tripling.
- CDC sentinel sites (Jul–Dec 2025): 10 of 20 testing sites found medetomidine in roughly a third of opioid-positive samples; 8 sites found it in more than half. 98% of medetomidine-positive samples had fentanyl co-detected.
- Regional split: Northeast 74.2% of opioid-positive samples · Midwest 56.2% · South 30.1% · West 3.8%.
- New York City deaths: 18 overdose deaths with medetomidine contributing in 2024 → 134 in 2025.
- BTMPS went from zero to top-12 in 18 months: first detected June 2024 (Portland, Philadelphia); by 2025 it was the 11th most-reported substance in NFLIS — an industrial plastic stabilizer with no antidote.
- Xylazine baseline: 30% of DEA-seized fentanyl powder in 2023 contained xylazine (25% in 2022); identified in seized samples in every US state, DC and Puerto Rico by 2024.
Context
US drug overdose deaths fell for a third straight year in 2025 — an estimated 69,973 deaths (provisional, −14%), with opioid-involved deaths down from 55,296 to 44,564. The adulterant problem is the reason these deaths are harder to reverse: an increasing share of the supply contains sedatives and industrial chemicals that naloxone was never designed to touch.
Methodology & sources
- DEA NFLIS-Drug — 2025 annual drug-case and report counts (nflis.deadiversion.usdoj.gov).
- DEA 2025 National Drug Threat Assessment — top-10 substances mixed with fentanyl, 2019 vs 2024; xylazine seizure geography; cocaine/meth co-detection rates.
- CDC Health Alert Network (April 2026) and CDC Overdose Prevention situation summary — medetomidine sentinel-site data and NFLIS trend counts.
- CDC NCHS (May 2026) — provisional 2025 overdose death estimates.
- JAMA research letter (March 2025) — BTMPS in the illicit fentanyl supply across nine US locations.
- Washington/Baltimore HIDTA bulletin (April 2025) — BTMPS spread and combination patterns.
Related: Fentanyl in numbers — the full guide · Fentanyl profile · Medetomidine profile · Xylazine profile · Overdose hotlines by region