Fen-Phen
Encyclopedic
Encyclopedic
Typical encyclopedia coverage. Cross-reference for important decisions.
- 2 corroborating sources
- descriptive-only dose data
- duration data present
- 18 combo interactions documented
- 2 corroborating sources
- descriptive-only dose data
- duration data present
- 18 combo interactions documented
Aliases: Phen/fen
Summary
Daily Fen-Phen use was linked to valvular heart disease and pulmonary hypertension via 5-HT2B receptor agonism by fenfluramine's metabolite norfenfluramine; the combination was withdrawn from market in 1997. Nearly 30% of users taking the combination for up to 24 months developed abnormal valve findings. Phentermine alone does not cause valvular damage and remains available for short-term obesity treatment.
Dose Information
Combination drug. Each cell below lists the two components' doses separated by “/” (e.g. “15–30mg / 30–60mg”). Because the components are distinct drugs on different dose scales, this per-component table replaces the single-axis dose chart.
Dose basis. Historical therapeutic ranges; not a recommendation. Fenfluramine carries dose- and duration-related risks of valvular heart disease and pulmonary arterial hypertension. Avoid redosing within 24–48 h due to long half-lives and accumulation. (Dose figures and this note are from Drugs.Wiki.)
| ROA | Light | Common | Strong | Heavy |
|---|---|---|---|---|
| Oral | 5-15mg / 10-30mg | 15-30mg / 30-60mg | 30-45mg / 60-80mg | 45mg+ / 80mg+ |
Onset, Duration & After-effects
| ROA | Onset | Comeup | Peak | Offset | Total |
|---|---|---|---|---|---|
| Oral | 20-60 min | 30-60 min | 1-3 hrs | 3-6 hrs | 4.83-11 hrs |
Effect Profile
Scores (1–10) curated from multiple sources:
- Effect keyword matching from PsychonautWiki catalog
- Weighted by importance: core (×3), major (×2), minor (×1)
Strong euphoria and anxiety/jitters with moderate stimulation, low focus
Add to PsychonautWiki Journal
The PsychonautWiki Journal logging app doesn't include every substance. To track Fen-Phen there, start adding an ingestion, search for the name, and choose to add it as a custom substance. Paste these values:
Fen-Phen Source: SubstanceSearch (substancesearch.com) Oral dose (mg): threshold 5 / 10 · light 5-15 / 10-30 · common 15-30 / 30-60 · strong 30-45 / 60-80 · heavy 45+ / 80+ Oral duration: onset 0.33-1h · come-up 0.5-1h · peak 1-3h · offset 3-6h · total 4.83-11h · after-effects 4-12h Note: ranges are harm-reduction guidance, not a prescription. Start low, go slow, and test your substances.
The app keeps custom substances simple, so the full dose ranges live in the description text above. Ranges are harm-reduction guidance, not a prescription.
Tolerance
Tolerance Decay
Acute tolerance: develops within a single session — the reset numbers above apply after sustained heavy use, not after one binge. Within-session tachyphylaxis usually resets largely overnight.
Tolerance to appetite suppression develops faster than to cardiovascular side effects; rest periods of several weeks reduce (but do not eliminate) risks. Data synthesized from clinical and anecdotal sources; quantitative estimates approximate.
Cross-Tolerances
Effects
- Stimulation
- Pain relief
- Physical euphoria
- Tachycardia
- Dry mouth
- Restlessness
- Insomnia
- Fatigue
- Respiratory depression
- Sedation
- Wakefulness
- Motivation enhancement
- Euphoria
- Alertness enhancement
- Cognitive euphoria
- Anxiety suppression
- Reduced anxiety
- Anxiety
- Constipation
- Talkativeness
- Warmth
- Increased music appreciation
- Increased libido
- Appetite suppression
- Light sensitivity
- Disinhibition
- Dehydration
- Dulled perception
- Internal hallucination
- Warm flush
Combinations
Cross-Check Fen-Phen with another substanceHelpful Links
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