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Fatal overdose may occur when GABAergic substances are combined with other depressants such as opiates, benzodiazepines, barbiturates, gabapentinoids, thienodiazepines or alcohol.[1]

It is strongly discouraged to combine these substances, particularly in common to heavy doses.

Summary sheet: Carisoprodol
Chemical Nomenclature
Common names Carisoprodol, Soma
Substitutive name Isopropyl meprobamate
Systematic name [2-(Carbamoyloxymethyl)-2-methylpentyl] N-propan-2-ylcarbamate
Class Membership
Psychoactive class Depressant
Chemical class Carbamate
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold 50 mg
Light 100 - 325 mg
Common 325 - 500 mg
Strong 500 - 750 mg
Heavy 750 mg +
Onset 15 - 60 minutes
Peak 2 - 5 hours
After effects 1 - 12 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


Carisoprodol, also known by the brand name Soma, is a carbamate sedative-hypnotic. Carisoprodol is used medically as a centrally-acting muscle relaxant, anxiolytic and hypnotic for the short-term treatment of insomnia. Carisoprodol also has weak analgesic effects. Carisoprodol is sometimes found in formulations also containing caffeine and acetaminophen. Carisoprodol produces similar effects to barbiturates. Carisoprodol acts as a prodrug to meprobamate, meaning it is metabolized to meprobamate when it enters the body.

Carisoprodol, like barbiturates, has been primarily replaced by benzodiazepines due to a larger therapeutic window, having less severe adverse effects and being safer in overdose.


Chemically, carisoprodol is classified as a carbamate. It is extremely similar in structure to meprobamate, the only difference being an isopropyl group bonded to an amine group. Carbamates are derivatives of carbamic acid. The empirical formula is carisoprodol is C12H24N2O4 and has a molar mass of 260.33 grams per mole.


Carisoprodol is a prodrug that is metabolized to meprobamate, besides having its own effects. The precise mechanism of meprobamate is not completely understood. However it is believed that meprobamate acts similarly to benzodiazepines and barbiturates, acting as a positive allosteric modulator of a GABAA receptor[2]. Unlike barbiturates and benzodiazepines, in animal studies meprobamate has been shown to retain most of its effects without having gamma-aminobutyric acid present[2]. Meprobamate has also been noted to be an adenosine reuptake inhibitor, making it unique among hypnotics[3].

Carisoprodol is metabolized by the cytochrome P450 2C19 enzyme in the liver and has a biological half-life of about two hours. Carisoprodol and its metabolites are excreted by the kidneys in urine.

Carisoprodol is a prodrug to meprobamate (pictured).

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

Visual effects

Cognitive effects

Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:

Toxicity and harm potential

Carisoprodol likely has moderate toxicity relative to dose. However, carisoprodol is potentially lethal when mixed with depressants like alcohol or opioids. Carisoprodol has been taken off the market is several countries such as Sweden and Indonesia due to side effects and abuse.

It is strongly recommended that one use harm reduction practices when using this drug.

Tolerance and addiction potential

Carisoprodol is extremely physically and psychologically addictive. Carbamate withdrawal, like barbiturate withdrawal, is medically serious and can potentially cause a life-threatening withdrawal syndrome that can cause seizures, psychosis, and death. Drugs which lower the seizure threshold such as tramadol and amphetamine should be avoided during withdrawal.

Tolerance will develop to the sedative-hypnotic effects of carisoprodol after prolonged use. It is unknown exactly how long it takes for tolerance to reach baseline.

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

  • Depressants (1,4-Butanediol, 2M2B, alcohol, benzodiazepines, barbiturates, GHB/GBL, methaqualone, opioids) - This combination potentiates the muscle relaxation, amnesia, sedation, and respiratory depression caused by one another. At higher doses, it can lead to a sudden, unexpected loss of consciousness along with a dangerous amount of depressed respiration. There is also an increased risk of suffocating on one's vomit while unconscious. If nausea or vomiting occurs before a loss of consciousness, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Dissociatives - This combination can unpredictably potentiate the amnesia, sedation, motor control loss and delusions that can be caused by each other. It may also result in a sudden loss of consciousness accompanied by a dangerous degree of respiratory depression. If nausea or vomiting occurs before consciousness is lost, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Stimulants - Stimulants mask the sedative effect of depressants, which is the main factor most people use to gauge their level of intoxication. Once the stimulant effects wear off, the effects of the depressant will significantly increase, leading to intensified disinhibition, motor control loss, and dangerous black-out states. This combination can also potentially result in severe dehydration if one's fluid intake is not closely monitored. If choosing to combine these substances, one should strictly limit themselves to a pre-set schedule of dosing only a certain amount per hour until a maximum threshold has been reached.

Legal status

In most jurisdictions, carisoprodol is considered a prescription-only and/or controlled drug.

  • Germany: Carisoprodol is a prescription medicine, according to Anlage 1 AMVV.[4]
  • United States: In the United States, carisoprodol is a Schedule IV Controlled Substance[5]. Therefore, it is prescription-only and anyone caught in possession of the substance with or without intent to distribute is punishable by law.

External links


  1. Risks of Combining Depressants - TripSit 
  2. 2.0 2.1 Rho, J. M., Donevan, S. D., Rogawski, M. A. (1 March 1997). "Barbiturate-Like Actions of the Propanediol Dicarbamates Felbamate and Meprobamate". Journal of Pharmacology and Experimental Therapeutics. 280 (3): 1383–1391. ISSN 0022-3565. 
  3. Phillis, J. W., Delong, R. E. (1 June 1984). "A purinergic component in the central actions of meprobamate". European Journal of Pharmacology. 101 (3–4): 295–297. doi:10.1016/0014-2999(84)90174-2. ISSN 0014-2999. 
  4. AMVV - Verordnung über die Verschreibungspflicht von Arzneimitteln 
  5. DEA Scheduled Drugs |