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Propylhexedrine

Propylhexedrine molecule structurePropylhexedrine molecule structure
1-cyclohexyl-N-methylpropan-2-amine
Benzedrex, ObesinOpen in Piru
Psychoactive Class
Chemical Class

Propylhexedrine is a stimulant1 classified as a cyclohexylalkylamine2, used medically in nasal inhalers to temporarily relieve congestion caused by colds and allergies.3 It was first used medically in 1949.2 It is structurally similar to methamphetamine, with a cyclohexane ring replacing the phenyl ring.4 Its free base is a volatile liquid that evaporates gradually, allowing administration by inhalation. Recreational use can be habit-forming.5

Dosage & Duration

Log in Piru

Dosage

Doses are population estimates that vary widely between individuals.

Threshold~5 mg
Light5-15 mg
Moderate15-30 mg
Strong30-50 mg
Heavy50+ mg

Subjective Effects

Subjective Effects not written up yet

Reagent Testing

Expected colorimetric results for common reagent tests. Colors show reaction change over 1–2 minutes.

Froe(FR)
white → purple2
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Pharmacology

Pharmacodynamics

Propylhexedrine promotes norepinephrine, dopamine, and serotonin release by reversing their transporters, increasing the availability of these neurotransmitters at synapses.6 It also antagonizes VMAT2, causing increased neurotransmitter release.6 Its TAAR1 agonism promotes dopamine transporter phosphorylation through protein kinase A and C signaling, contributing to dopamine reuptake inhibition and transporter reversal. Propylhexedrine also acts as an alpha-adrenergic agonist7, producing blood vessel constriction, and modulates the alpha-2C adrenergic receptor.

Pharmacokinetics

Propylhexedrine is metabolized through N-demethylation, C-oxidation, N-oxidation, dehydrogenation, and hydrolysis. Cytochrome P450 enzymes contribute to its metabolism, with computational predictions identifying CYP2D6 as a substrate pathway. Its reported elimination half-life is 2.5-6.5 hours; higher urinary pH slows elimination, while lower urinary pH and greater activity of certain cytochrome P450 enzymes speed it up. Computational predictions also suggest intestinal absorption, blood-brain barrier penetration, and permeability across Caco-2 intestinal cell models. These predictions classify it as neither a P-glycoprotein substrate nor inhibitor, neither a CYP2C9 nor CYP3A4 substrate, and a non-inhibitor of the renal organic cation transporter and CYP1A2, CYP2C9, CYP2D6, CYP2C19, and CYP3A4.

Interactions

Dangerous

Highest risk

These combinations are considered extremely harmful and should always be avoided. Reactions to these drugs taken in combination are highly unpredictable and have a potential to cause death.

AlcoholCocaineDXMDissociativesMAOIsMDMAMXENBOMe compoundsStimulantsTramadolTricyclic antidepressants

Caution

Use caution

These combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.

AcebutololAlfuzosinAlprenololAmineptineAmitriptyline
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Tolerance

Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.

Full Tolerance
Tolerance may develop with chronic propylhexedrine use and likely builds rapidly during prolonged, repeated use, following a pattern similar to amphetamine.
Baseline Reset
Without further consumption, tolerance likely returns to baseline within approximately 1–2 weeks.
Half Tolerance
Without further consumption, tolerance likely falls to approximately half its previous level within 3–7 days.
Cross Tolerance

All dopaminergic stimulants

Harm Potential

Addiction & Dependence

Psychological

High

Chronic propylhexedrine use is described as highly addictive, although its overall abuse potential is assessed as moderate. Psychological dependence can develop, with cravings after abrupt cessation or a substantial reduction in use.

Physical

Chronic propylhexedrine use can produce physical dependence and tolerance. Withdrawal effects may occur when dependent users abruptly stop or substantially reduce use.

Toxicity

Lethal Dosage

Recreational misuse of propylhexedrine products has caused fatalities,5 and injection increases the risks associated with recreational use. Overdoses most often involve recreational administration inconsistent with product labeling.

Cardiovascular

Propylhexedrine increases heart rate and blood pressure and constricts blood vessels; palpitations are commonly reported at common to heavy doses. Recreational misuse can cause serious cardiovascular complications, including rapid or abnormal heart rhythms, hypertension, and chest pain, with possible hospitalization, disability, or death.5

Nasal mucosa

Propylhexedrine administered by inhaler may cause temporary nasal burning or stinging, and frequent or prolonged use may cause nasal congestion to worsen or recur.8

Psychosis Risk

Propylhexedrine abuse can cause stimulant-induced psychosis with paranoia, hallucinations, and delusions; psychosis is also reported in acute overdose. Serious psychiatric complications associated with misuse can require hospitalization or cause disability.5

History & Culture

Development and medical introduction

Propylhexedrine was developed during a search for safer nasal decongestants. In 1948, Dr. Glenn E. Ullyot patented its use as a decongestant for Smith, Kline & French. Market trials in California began on July 15, 1949, before its national introduction in the United States. Smith, Kline & French…

Legality

International

Controlled internationally under the UN Convention on Psychotropic Substances 1971.

By Country

Illegal1
United Kingdom flagUnited KingdomIllegal (analog/blanket ban)
Prescription3
Australia flagAustraliaPrescription only
Brazil flagBrazilPrescription only
Germany flagGermanyPrescription only
Not scheduled3
United States flagUnited StatesNot scheduled
Canada flagCanadaNot scheduled
Switzerland flagSwitzerlandNot scheduled

References

Source Pages

  1. Erowid
  2. Erowid: Propylhexedrine Vault
  3. Isomer Design (TiHKAL/PiHKAL)
  4. PsychonautWiki
  5. TripSit Factsheets
  6. Wikipedia

Citations

  1. Propylhexedrine. WHO Expert Committee on Drug Dependence Information Repository (n.d.). https://ecddrepository.org/en/propylhexedrine1
  2. Neurologic Deficits Following Oral Misuse of the Nasal Decongestant Propylhexedrine. Journal of Medical Toxicology (2024). https://doi.org/10.1007/s13181-024-01025-w12
  3. Benzedrex — propylhexedrine inhalant. DailyMed (2024). https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=00d8c237-3eee-1d9f-e063-6394a90aeb861
  4. The stimulants and hallucinogens under consideration: A brief overview of their chemistry and pharmacology. Drug and Alcohol Dependence (1986). https://doi.org/10.1016/0376-8716(86)90002-51
  5. FDA warns that abuse and misuse of the nasal decongestant propylhexedrine causes serious harm. U.S. Food and Drug Administration (2021). https://www.fda.gov/drugs/drug-safety-and-availability/fda-warns-abuse-and-misuse-nasal-decongestant-propylhexedrine-causes-serious-harm1234
  6. Propylhexedrine: Uses, Interactions, Mechanism of Action. DrugBank (n.d.). https://go.drugbank.com/drugs/DB0671412
  7. PubChem PUG View record for Propylhexedrine (CID 7558), Pharmacodynamics. pubchem.ncbi.nlm.nih.gov (n.d.). https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/7558/JSON1
  8. Propylhexedrine (Monograph). American Society of Health-System Pharmacists / Drugs.com (2025). https://www.drugs.com/monograph/propylhexedrine.html?references=11
  9. Prince v. B.F. Ascher Company, Inc.. Court of Civil Appeals of Oklahoma, reproduced by CaseMine (2004). https://www.casemine.com/judgement/us/591477edadd7b049343dc2dc1
  10. Pfizer Completes Acquisition Of Wyeth. Pfizer (2009). https://www.pfizer.com/news/press-release/press-release-detail/pfizer_completes_acquisition_of_wyeth1

Further Reading

  1. FDA Warning on Propylhexedrine Abuse
  2. Midha et al. 1974 - Metabolites of Propylhexedrine
  3. Poison Control: Propylhexedrine

Article Status

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