Opioids
Para-fluorofentanyl (4-FBF)
Street names: pFF, 4-FBF, Fluorofentanyl
Overdose? Act now. Call emergency services — say "unresponsive, not breathing". Give naloxone for opioid-like signs. Hotlines
⚡What it does
- Fentanyl-family opioid — same warmth, sedation and euphoria, typically described as slightly longer-acting than fentanyl itself
- Roughly comparable overdose potency to fentanyl by weight; effects outlast the initial rush
- Same instant dependence pattern: tolerance within days, withdrawal within weeks
⚠Key risks
- The most-reported fentanyl analogue in DEA forensic casework — when a seizure report says 'fentanyl analogue,' this is often the molecule
- Presence in cocaine supplies means stimulant users with zero opioid tolerance are overdosing without ever choosing an opioid
- Naloxone reverses it, but long-acting analogues can re-sedate after naloxone wears off — stay with the person until help arrives
- Pressed 'oxy 30s' containing pFF instead of oxycodone have killed people who thought they were taking a known dose
- Same adulterant trajectory: dealers mix it with xylazine, medetomidine and cutting agents like BTMPS
✚Overdose signs
- Unrousable, slow or absent breathing
- Blue lips or fingertips; cold, clammy skin
- Gurgling or snoring sounds — naloxone now, rescue breathing, emergency call
Category comparison — Opioids
| Substance | Class | Top risks | Street price |
|---|---|---|---|
| Para-fluorofentanyl (4-FBF) | Schedule I | The most-reported fentanyl analogue in DEA forensic casework — when a seizure report says 'fentanyl analogue,' this is often the molecule; Presence in cocaine supplies means stimulant users with zero opioid tolerance are overdosing without ever choosing an opioid | ~$15–40/g wholesale |
| Heroin | Schedule I | Extremely addictive — physical dependence in weeks; Overdose: breathing slows or stops | ~$10–$40 per bag |
| Fentanyl | Schedule II | Respiratory depression; Addiction in days | ~$20–$40 per counterfeit pill |
| Fentanyl HCl (powder) | Schedule II / analogue prosecutions | Lab-purity powder is far stronger than street mixes; Weighing errors are fatal | ~$60–$120/gram wholesale equivalent |
| Acetylfentanyl | Schedule I | ~5–15× weaker than fentanyl but still deadly at gram-level mistakes; Frequent cause of cluster overdoses | ~$25–$60/g where found |
| Furanylfentanyl (Fu-F) | Schedule I | Linked to hundreds of fatal overdoses 2016–2018; Potency similar to fentanyl | ~$20–$50/g |
Street prices are regional estimates. Potency and cuts vary constantly.
?Frequently asked questions
What does Para-fluorofentanyl (4-FBF) look like?
White to off-white powder; found loose, in fake oxycodone pills, and mixed into heroin and cocaine supplies
What are the signs of a Para-fluorofentanyl (4-FBF) overdose?
Unrousable, slow or absent breathing; Blue lips or fingertips; cold, clammy skin; Gurgling or snoring sounds — naloxone now, rescue breathing, emergency call Call emergency services immediately and give naloxone if available — it reverses opioid overdoses.
How addictive is it?
The most-reported fentanyl analogue in DEA forensic casework — when a seizure report says 'fentanyl analogue,' this is often the molecule Dependence can develop with regular use.
🔗Sources & further reading
Facts on this page are compiled from these primary sources. External links open in a new tab.