GHB / GBL
F-Phenibut (Fluorophenibut)
Street names: F-Phenibut, 4F-Phenibut, Fluorobut
Overdose? Act now. Call emergency services — say "unresponsive, not breathing". Give naloxone for opioid-like signs. Hotlines
⚡What it does
- Same as phenibut (calm, sociability) but stronger and longer
⚠Key risks
- Same brutal dependence/withdrawal — the fluorine just means smaller doses make the same trap
- Dose-error risk: users dosing by phenibut habits overdose
- Withdrawal: anxiety, insomnia, psychosis, seizures
- No regulation = no quality control
✚Overdose signs
- Extreme sedation
- Slow breathing (with other depressants)
📋Quick facts
Also known asF-Phenibut, 4F-Phenibut, Fluorobut
CategoryGHB / GBL
Schedule / classUnscheduled grey market
AppearanceWhite powder/capsules — fluorinated phenibut, several-fold more potent
Street price$20–$50 per 10 g
Legal statusUnscheduled; 'research' gray market
Last updated2026-09-18
Sources: TripSit, EMCDDA
Category comparison — GHB / GBL
| Substance | Class | Top risks | Street price |
|---|---|---|---|
| F-Phenibut (Fluorophenibut) | Unscheduled grey market | Same brutal dependence/withdrawal — the fluorine just means smaller doses make the same trap; Dose-error risk: users dosing by phenibut habits overdose | $20–$50 per 10 g |
| Phenibut | Not scheduled US | RAPID TOLERANCE — daily use creates dependence in 2–3 weeks; Withdrawal is BRUTAL and dangerous: severe anxiety, insomnia, hallucinations, psychosis, seizures — worse than benzodiazepine withdrawal for some | ~$20–$50 per 50g powder |
| Phenibut FAA (Free Amino Acid) | Unscheduled; sold as supplement | Same brutal withdrawal (anxiety, insomnia, psychosis, seizures); FAA form marketed as 'stronger' — overdose temptation | $20–$50 per 50g |
| Baclofen (Lioresal) | Rx-only — not controlled | ABRUPT STOP AFTER LONG USE = SEIZURES/RHABDO/psychosis — the withdrawal is genuinely dangerous and under-warned; Sedation, hypotension | ~$0.30–$1 per tablet grey-market |
Street prices are regional estimates. Potency and cuts vary constantly.
?Frequently asked questions
What does F-Phenibut (Fluorophenibut) look like?
White powder/capsules — fluorinated phenibut, several-fold more potent
What are the signs of a F-Phenibut (Fluorophenibut) overdose?
Extreme sedation; Slow breathing (with other depressants) Call emergency services immediately.
How addictive is it?
Same brutal dependence/withdrawal — the fluorine just means smaller doses make the same trap Withdrawal can be life-threatening — medical tapering is essential.