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Carisoprodol
Isopropyl meprobamate
Soma, Vanadom, Rela, Carisoma, Somadril
Carisoprodol is a carbamate sedative-hypnotic and centrally acting muscle relaxant first approved for medical use in 1959.citation needed Developed as an improvement upon meprobamate, it functions as a prodrug that is metabolized into meprobamate in the body. Prescribed for the short-term treatment of musculoskeletal pain, it also possesses anxiolytic and hypnotic properties. Its effects are often compared to barbiturates, and it has been largely supplanted by benzodiazepines due to safety concerns. Its European Union approval was withdrawn in 2008.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Threshold50 mg
Light100-350 mg
Moderate350-500 mg
Strong500-700 mg
Heavy700+ mg
Duration
Onset15-60 minutes
Peak2-5 hours
After Effects1-12 hours
Half-life
~2 hours
Subjective Effects
Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.
The experience is dominated by sedation, muscle relaxation, and anxiety relief, with an overall character frequently compared to barbiturates, benzodiazepines, and alcohol. At common doses the effects are often unremarkable, a heady, dreamy lethargy with relaxation but little mood lift, while stronger doses more reliably produce cognitive and physical euphoria, and very high doses are associated with a hypomanic-like state of cheerfulness, disinhibition, sociability, and psychomotor excitement alongside marked impairment. Any euphoria tends to be short-lived owing to the drug's rapid metabolism into meprobamate, and is thought to stem largely from carisoprodol's potent anxiolytic action. Responses vary considerably: even at high doses, some users primarily encounter sedation, depression, and dysphoria rather than positive effects.
Physical
The body feel centers on heavy sedation and pronounced muscle relaxation, accompanied by lethargy, dizziness, and impaired coordination. Physical euphoria at stronger doses is often described as more prominent than that of benzodiazepines.
Cognitive
The headspace is relaxed, anxiolytic, and somewhat zoned-out, with disinhibition and increased sociability emerging at stronger doses. Memory of the experience can be impaired, and total amnesia of the period after ingestion is not uncommon following heavy use or overdose.
Emotional
Suppressions
Visual
Visual effects are largely absent at typical doses; blurred vision and nystagmus are associated with overdose.
Pharmacology
Pharmacodynamics
Carisoprodol is a centrally acting muscle relaxant that functions through both positive allosteric modulation and direct agonism at GABA-A receptors, with evidence suggesting separate binding sites for each mechanism, both of which appear distinct from those used by benzodiazepines and barbiturates.1 Its muscle relaxant effects are associated with altered interneuronal activity in the spinal cord and descending reticular formation.citation needed The drug shows subunit-dependent selectivity, with direct agonist activity more pronounced at α2-containing receptors and positive allosteric modulation showing greater efficacy at α1 and β2-containing complexes. In animal studies, flumazenil has been shown to partially inhibit the drug's activity.
Pharmacokinetics
Carisoprodol is metabolized in the liver primarily by CYP2C19, with a considerable proportion converted to meprobamate, an active metabolite that functions as a GABA-A receptor modulator and adenosine reuptake inhibitor.citation needed Meprobamate reaches higher peak plasma concentrations than carisoprodol itself and has a substantially longer half-life of approximately 11.3 hours. Additional metabolites include hydroxycarisoprodol and hydroxymeprobamate. The reported elimination half-life of carisoprodol is approximately 2 hours according to some sources and approximately 8 hours according to others. Excretion occurs via the kidneys.2
Dangerous
Highest riskThese 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.
DissociativesStimulants
Caution
Use cautionThese 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.
1,2-BenzodiazepineAbataceptAbrocitinibAcenocoumarolAcetazolamide
Tolerance
Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.
Full Tolerance
Tolerance develops to the sedative-hypnotic effects following prolonged use. The accumulation of the active metabolite meprobamate, which has a longer half-life, contributes to the development of tolerance and complicates the tolerance profile with chronic administration.
Cross Tolerance
Other carbamates (meprobamate), Barbiturates, GABAergic sedative-hypnotics
Baseline Reset
The exact timeframe for tolerance to return to baseline is not well established. Due to the accumulation of meprobamate with chronic use, complete tolerance reset may require an extended period of abstinence.
Harm Potential
Addiction & Dependence
Psychological
HighCarisoprodol has significant psychological addiction potential with documented abuse cases even when used without other drugs possessing abuse potential.citation needed Compulsive redosing is a recognized effect, and users frequently escalate to very high daily doses. Its potent anxiolytic effects and euphoria are implicated in drug-seeking behavior. Psychological dependence is more common in those who use it non-medically or have a history of substance use.
Physical
Extremely HighPhysical dependence of the barbiturate type develops following prolonged use.citation needed Withdrawal can be life-threatening, particularly in high-dose users or those who stop abruptly, and may require hospitalization. Severe withdrawal can mimic alcohol withdrawal including potentially lethal status epilepticus. The accumulation of meprobamate, which has a longer half-life, contributes to withdrawal severity.
Toxicity
Central Nervous System
Overdose causes CNS depression ranging from lethargy to deep coma; chronic use and withdrawal can result in prolonged cognitive changes including memory impairment, reduced IQ, increased anxiety and depression, and in some cases these effects persist for months or years after discontinuation.citation needed
Respiratory
Respiratory depression occurs primarily in overdose situations and is significantly more dangerous when carisoprodol is combined with other CNS depressants; mechanical ventilation may be required in severe cases.citation needed
Psychosis Risk
Psychotic symptoms occur primarily during withdrawal rather than acute intoxication.citation needed Approximately 20% of withdrawal cases feature hallucinations (mainly visual and auditory) or other psychotic symptoms. Case reports document patients experiencing vivid hallucinations of insects, animals, people, and voices indistinguishable from reality, along with paranoid ideation. Symptoms typically peak 3-5 days after cessation and may last up to 8-9 days.
Seizure Risk
Unlike benzodiazepines, carisoprodol increases rather than decreases seizure risk.citation needed Seizures can occur both in overdose and during withdrawal. Withdrawal seizures can progress to potentially lethal status epilepticus, similar to alcohol withdrawal. Drugs that lower seizure threshold should be avoided during withdrawal. Deaths have been reported in association with carisoprodol-related seizures.
History & Culture
Discovery and Development
Frank M. Berger at Wallace Laboratories (later Carter-Wallace) synthesized carisoprodol in 1956.citation needed Berger had also been part of the team responsible for creating meprobamate, which had become a widely used pharmaceutical during the 1950s. The development of…
Legality
International
1961 Single Convention: carisoprodol is not scheduled.
1971 Convention on Psychotropic Substances: Schedule IV.
1988 Convention: carisoprodol is not listed in precursor Tables I or II.
By Country
Illegal1
ThailandIllegalThe current Thai FDA schedule expressly classifies Carisoprodol in Category III. The FDA's current restrictions make Schedule III/IV import, export and possession unlawful without Ministry of Public Health permission, while preserving the stated medical-use and traveler limits (up to 30 days without a permit; 31 to 90 days with a permit and medical documentation). Categories III and IV are medically useful but authorization-controlled. The Medicines Regulation Division has a dedicated ministerial-order entry for Carisoprodol. Current rules provide no general no-prescription availability or exemption for OTC combination products.
Controlled / restricted2
CanadaRestrictedControlled Drugs and Substances Act and regulations10
Current official national law establishes the stated carisoprodol control in Canada; lawful medical handling remains subject to the cited regime.
SpainRestrictedSpanish AEMPS medicinal-product suspension notices16
The AEMPS notice imposes a regulatory suspension on authorized medicinal products and their marketing and dispensing; it does not concern over-the-counter availability or a general criminal scheduling statute.
Prescription3
United StatesPrescription only21 CFR § 1308.14(c)21
Current official national law establishes the stated carisoprodol control in United States; lawful medical handling remains subject to the cited regime.
GermanyPrescription onlyBetäubungsmittelgesetz, Anlage III11
Carisoprodol is listed in Anlage III of the BtMG as a marketable and prescribable controlled substance.
MexicoPrescription onlyThe current Mexican statute expressly lists CARISOPRODOL in Article 245 fraction III and applies Article 251's physician-prescription, professional-license-number, one-time-fill, and pharmacy-retention controls. The Health Ministry regulation reinforces those controls through written-prescription identity requirements in Article 1180 and pharmacy retention/control requirements for Group III prescriptions in Article 1182. Carisoprodol is supplied by prescription under these controls, and its classification does not constitute an absolute prohibition.
Not scheduled6
AustraliaNo longer registeredRemoved from the Australian Register of Therapeutic Goods. Access is still possible through the Special Access Scheme for individual patient needs.9
European UnionMarketing authorization withdrawnThe European Medicines Agency recommended member states suspend marketing authorization in 2008 due to concerns about dependence and insufficient benefit-risk profile for acute back pain treatment.7
FinlandNo longer availableCarisoprodol is no longer available in Finland, including as a prescription medication.7 Previously marketed as Somadril.citation needed
IndonesiaWithdrawn from marketTaken off the market in September 2013 due to concerns about diversion, dependence, and adverse effects.9
SwedenWithdrawn from marketTaken off the market in November 2007 due to problems with dependence and side effects.7 The Swedish pharmaceutical regulatory agency determined that alternative medications offered comparable or better efficacy without the associated risks.citation needed
References
Source Pages
Citations
- Assessment of Subunit-Dependent Direct Gating and Allosteric Modulatory Effects of Carisoprodol at GABAA Receptors. (n.d.). https://pmc.ncbi.nlm.nih.gov/articles/PMC4737552/1
- SOMA- carisoprodol tablet (DailyMed, setid 6543c6ba). (n.d.). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6543c6ba-852e-40fb-b7ec-1331b9c8365612
- Carisoprodol - StatPearls. (n.d.). https://www.ncbi.nlm.nih.gov/books/NBK553077/1
- Carisoprodol dependence: a case report. (n.d.). https://pubmed.ncbi.nlm.nih.gov/755391/1
- The Pharmacology and Toxicology of the 'Holy Trinity'. Basic & Clinical Pharmacology & Toxicology, 120(2), 115–119 (February 2017). https://doi.org/10.1111/bcpt.126551
- The Patriot's Skye McCole Bartusiak Died of Accidental Overdose. (n.d.). https://www.eonline.com/news/588153/the-patriot-s-skye-mccole-bartusiak-died-of-accidental-overdose1
- European Medicines Agency recommends suspension of marketing authorisations for carisoprodol-containing medicinal products. (n.d.). https://www.ema.europa.eu/en/news/european-medicines-agency-recommends-suspension-marketing-authorisations-carisoprodol-containing-medicinal-products12345
- Schedules of Controlled Substances: Placement of Carisoprodol Into Schedule IV (76 FR 77330). (n.d.). https://www.federalregister.gov/documents/2011/12/12/2011-31542/schedules-of-controlled-substances-placement-of-carisoprodol-into-schedule-iv1
- ACMD report: A review of the evidence on the use and harms of carisoprodol. (n.d.). https://www.gov.uk/government/publications/carisoprodol-review-of-the-evidence-on-its-use-and-harms/acmd-report-a-review-of-the-evidence-on-the-use-and-harms-of-carisoprodol-accessible12
- Controlled Drugs and Substances Act and regulations. laws-lois.justice.gc.ca (n.d.). https://laws-lois.justice.gc.ca/eng/acts/C-38.8/FullText.html1
Article Status
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Recent changes8 human edits · latest
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26 August 2026
Lyrea · Reworded 4 words in Subjective Effects › Notes › Overview
Lyrea · Changed a word in Dosage & Duration › Routes 1 › Dose ranges › Heavy
Lyrea · Changed a word in Dosage & Duration › Routes 1 › Dose ranges › Strong
Lyrea · Changed a word in Dosage & Duration › Routes 1 › Dose ranges › Moderate
24 January 2026
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
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