4F-PHP is a potent synthetic stimulant in the pyrrolidinophenone/cathinone class, structurally related to alpha-PHP with a fluorine substitution at the 4-position of the phenyl ring. First identified in 2017, it produces strong stimulation and euphoria with high compulsivity. User reports suggest it is slightly less prone to extreme side effects than alpha-PVP but still carries significant risks including cardiovascular strain, anxiety, paranoia, and stimulant psychosis. Limited clinical data exists. Harm reduction practices are essential, including accurate dosing with a milligram scale, avoiding prolonged binges, and maintaining hydration.
Also known as: 4-fluoro-alpha-php, 4-fluoro-pyrrolidinohexanophenone
Classification
Chemical: Cathinone
Psychoactive: Stimulant
Tag: Habit-Forming
Tag: Pyrrolidine
Tag: Research-Chemical
Tag: Tentative
Effects
Stimulation
Increased Heart Rate
Increased Perspiration
Teeth Grinding
Insomnia
Vasoconstriction
Euphoria
Cognitive Euphoria
Focus Enhancement
Ego Inflation
Compulsive Redosing
Thought Acceleration
Increased Libido
Tactile Enhancement
Disinhibition
Appetite Suppression
Light Sensitivity
Dehydration
Routes of Administration
Oral
Dosage
Threshold: <5 mg
Light: 5-10 mg
Common: 10-25 mg
Strong: 25-40 mg
Heavy: >40 mg
Duration
Onset: 0.17-0.5 h
Comeup: 0.33-0.67 h
Peak: 1-3 h
Offset: 2-4 h
After Effects: 4-24 h
Total Duration: 4-8 h
Insufflated
Dosage
Threshold: <3 mg
Light: 5-15 mg
Common: 15-30 mg
Strong: 30-50 mg
Heavy: 50 mg
Duration
Onset: 0.03-0.17 h
Comeup: 0.17-0.33 h
Peak: 0.5-2 h
Offset: 1-3 h
After Effects: 4-24 h
Total Duration: 3.5-7 h
Vaporized
Dosage
Threshold: <2 mg
Light: 2-5 mg
Common: 5-10 mg
Strong: 10-20 mg
Heavy: 20 mg
Duration
Onset: 0.02-0.08 h
Comeup: 0.08-0.17 h
Peak: 0.25-0.75 h
Offset: 0.5-1.5 h
After Effects: 2-12 h
Harm Reduction
Check interactions before mixing substances, pay attention to dose spacing and hydration, and treat all dosage guidance as approximate rather than guaranteed safe.
Sources
Substance data is aggregated from the following public harm-reduction and reference sources.
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4F-PHP - Guide des substances DrugsPRO
4F-PHP: 4F-PHP is a potent synthetic stimulant in the pyrrolidinophenone/cathinone class, structurally related to alpha-PHP with a fluorine substitution at the 4-position of the phenyl ring. First identified in 2017, it produces strong stimulation and euphoria with high compulsivity. User reports su
