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Class: Centrally Acting Skeletal Muscle Relaxants
VA Class: MS200
CAS Number: 78-44-4
Brands: Soma

Medically reviewed by Last updated on Feb 24, 2020.


Skeletal muscle relaxant; structurally and pharmacologically related to meprobamate.100 a

Uses for Carisoprodol

Muscular Conditions

Short-term (i.e., up to 2–3 weeks) relief of discomfort associated with acute, painful musculoskeletal conditions.29 100 101 102 Indicated for short-term use only;100 prolonged use not adequately studied and may increase risk of abuse, dependence, and tolerance.100 113 114 117

If pharmacologic therapy is required for acute low back pain (usually a benign and self-limiting condition105 106 108 ), experts state that an NSAIA or skeletal muscle relaxant may be considered.209 Skeletal muscle relaxants may provide small improvements in pain relief, but are associated with a high incidence of adverse effects (e.g., CNS effects).104 106 107 108 209 Use with caution after weighing risks against benefits.104 106 107 108

Various skeletal muscle relaxants appear to have comparable efficacy for low back pain relief.103 104 106 108

Carisoprodol is ineffective for treatment of skeletal muscle hyperactivity secondary to chronic neurologic disorders (e.g., cerebral palsy) and other dyskinesias.25 29

Carisoprodol Dosage and Administration


Administer orally with or without food.100



Muscular Conditions

250–350 mg 3 times daily and at bedtime.100

Prescribing Limits


Muscular Conditions

Do not administer for more than 2–3 weeks.100

Cautions for Carisoprodol


  • History of acute intermittent porphyria.100

  • Known hypersensitivity to carisoprodol or other carbamate derivatives (e.g., meprobamate).100


Sensitivity Reactions

Hypersensitivity Associated with Meprobamate

Allergic or idiosyncratic reactions have been reported in patients receiving meprobamate, a metabolite of carisoprodol.109

Reactions may be mild (e.g., pruritus, urticaria, erythematous maculopapular rash) or more severe (e.g., hyperpyrexia, chills, angioedema, bronchospasm, anaphylaxis, stomatitis, proctitis, oliguria, anuria, exfoliative dermatitis, erythema multiforme, Stevens-Johnson syndrome, bullous dermatitis).109 Leukopenia, acute nonthrombocytopenic purpura, petechiae, ecchymoses, eosinophilia, adenopathy, peripheral edema, fever, and fixed drug eruptions with cross-reaction to carisoprodol also reported.109

General Precautions

CNS Effects

Possible drowsiness and dizziness.100 Vertigo, ataxia, tremor, agitation, irritability, headache, depressive reaction, syncope, and insomnia also reported.100

Seizures have been reported, mostly in setting of multiple-drug overdoses (including drugs of abuse, illicit drugs, and alcohol).100

Performance of activities requiring mental alertness or physical coordination may be impaired.100 Carisoprodol use has been associated with motor vehicle accidents.100 114

Concurrent use of other CNS depressants may potentiate CNS effects.100 122 (See Specific Drugs under Interactions.)

Abuse, Dependence, and Withdrawal

Subject to control as a schedule IV drug.100 Potential for abuse, misuse, and diversion.100 108 113 114 117 118 Risk of abuse is greater with prolonged use and also in patients with a history of drug abuse or receiving other drugs with abuse potential (e.g., opiate analgesics, benzodiazepines, illicit drugs).100 108 112 114 115 118

Both carisoprodol and its main active metabolite (meprobamate) may contribute to abuse potential.100 106 112 113 114 117 118 119

Tolerance and physical dependence can occur with prolonged use.100 Withdrawal symptoms (e.g., hallucinations, tremors, anxiety, muscle twitching, insomnia) reported following abrupt cessation of therapy after prolonged use.100 113 117 Instruct patients receiving large doses or prolonged therapy to not abruptly discontinue the drug.100

Assess abuse potential prior to use.100 Take special precautions during treatment to reduce risk of abuse (e.g., limit use to short periods of ≤3 weeks, maintain careful prescription records, monitor for signs of abuse and overdosage, educate patients and family members on abuse and proper storage and disposal of the drug).100

GI Effects

Nausea, vomiting, and epigastric distress have been reported.100 a

Cardiovascular Effects

Tachycardia, postural hypotension, and facial flushing have been reported.100 a

Fixed Combinations

When used in fixed combination with aspirin and/or codeine, consider the cautions, precautions, and contraindications associated with the other agent(s).123 124

Specific Populations


No evidence of drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes with use of carisoprodol or meprobamate (an active metabolite) during pregnancy.100 In animal reproductive studies, reduced fetal weights, postnatal weight gain, and postnatal survival observed.100


Distributed into milk; may reach concentrations that are 2–4 times maternal plasma concentrations.100 110 125 Not known whether the drug affects milk production.100 Consider known benefits of breastfeeding along with mother's clinical need for carisoprodol and any potential adverse effects on the nursing infant from the drug or underlying maternal condition.100 Monitor nursing infant for signs of sedation during breastfeeding.100

Pediatric Use

Safety and efficacy not established in children <16 years of age.100

Geriatric Use

Safety and efficacy not established in geriatric patients >65 years of age.100

Because of risk of injury, skeletal muscle relaxants should generally be avoided in geriatric patients.111

Hepatic Impairment

Use with caution; metabolized by the liver.100 a

Renal Impairment

Use with caution; excreted by the kidneys.100 a

Pharmacogenomics and Effects of CYP2C19 Polymorphism

Use with caution in patients with reduced CYP2C19 activity (i.e., poor metabolizers); potential for increased exposure to carisoprodol.100 120 (See Absorption: Special Populations, under Pharmacokinetics.)

Common Adverse Effects

Drowsiness, dizziness, headache.100

Interactions for Carisoprodol

Metabolized by CYP2C19.100

Drugs Affecting Hepatic Microsomal Enzymes

CYP2C19 inhibitors: Potential pharmacokinetic interaction (increased exposure to carisoprodol and decreased exposure to meprobamate).100 Clinical importance unknown.100

CYP2C19 inducers: Potential pharmacokinetic interaction (decreased exposure to carisoprodol and increased exposure to meprobamate).100 Clinical importance unknown.100

Specific Drugs





Potential additive CNS depression 100

Avoid concomitant use100


Possible decreased exposure to carisoprodol and increased exposure to meprobamate100

Clinical importance unknown100

CNS depressants (e.g., benzodiazepines, opiate agonists, sedating antihistamines, tricyclic antidepressants)

Potential additive CNS depression 100 122

Use concomitantly with caution100 122


Possible increased exposure to carisoprodol and decreased exposure to meprobamate100

Clinical importance unknown100


Additive pharmacologic effects since meprobamate is active metabolite of carisoprodol100

Avoid concomitant use100


Possible increased exposure to carisoprodol and decreased exposure to meprobamate100

Clinical importance unknown100


Possible decreased exposure to carisoprodol and increased exposure to meprobamate100

Clinical importance unknown100

St. John's wort (Hypericum perforatum)

Possible decreased exposure to carisoprodol and increased exposure to meprobamate100

Clinical importance unknown100

Carisoprodol Pharmacokinetics



Peak plasma concentrations achieved in approximately 1.5–2 hours.100 121


High-fat meal does not affect pharmacokinetics.100


Usually within 30 minutes.a


4–6 hours.a

Special Populations

Patients who are poor metabolizers of CYP2C19 may have fourfold increase in carisoprodol exposure and 50% decrease in meprobamate exposure compared with individuals with normal CYP2C19 function.100 (See Pharmacogenomics and Effects of CYP2C19 Polymorphism under Cautions.)



Crosses the placenta; distributes into milk in concentrations 2–4 times higher than concurrent maternal plasma concentrations.100 110 125



Metabolized in the liver by CYP2C19.100 112

Several metabolites (meprobamate, hydroxycarisoprodol, hydroxymeprobamate) identified; meprobamate is main active metabolite.100 112 117

Elimination Route

Eliminated via both renal and nonrenal routes.100


Carisoprodol: About 2 hours.100 121

Meprobamate: About 10 hours.100 121

Special Populations

May be removed by hemodialysis or peritoneal dialysis.100 Accumulation of carisoprodol may occur in patients with hepatic or renal impairment.100





20–25°C in tight containers.100

Fixed-combination preparation with aspirin and codeine: Tight, light-resistant containers at 20–25°C; protect from moisture.123

Fixed-combination preparation with aspirin: Tight, light-resistant containers at 20–25°C; protect from moisture.124


  • CNS depressant with sedative and skeletal muscle relaxant effects.100 a

  • Precise mechanism of action not known; minimal skeletal muscle relaxant effects probably are related to sedation.100 a

  • No direct skeletal muscle relaxant effect;100 a does not depress neuronal conduction, neuromuscular transmission, or muscle excitability.a

  • In animals, blocks interneuronal activity in descending reticular formation and spinal cord.100

  • May modify central perception of pain without abolishing peripheral pain reflexes and may have slight antipyretic activity.25 27

Advice to Patients

  • Potential for drug to cause drowsiness or dizziness and to impair mental alertness or physical coordination; use caution when driving or operating machinery until effects on individual are known.100

  • Potential for additive CNS depression if alcohol, benzodiazepines, opiate agonists, tricyclic antidepressants, sedating antihistamines, or other sedatives are used concomitantly.100 Importance of avoiding alcohol during therapy.100

  • Risk of possible dependence, withdrawal, and abuse with prolonged therapy.100

  • Importance of limiting use to short term (up to 2–3 weeks).100

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.100

  • Importance of women informing their clinician if they are or plan to become pregnant or plan to breast-feed.100

  • Importance of informing patients of other important precautionary information.100 (See Cautions.)


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Carisoprodol is subject to control under the Federal Controlled Substances Act of 1970 as a schedule IV (C-IV) drug.100 Preparations containing the drug combined with codeine phosphate are subject to control as schedule III (C-III) drugs.123

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name



Dosage Forms


Brand Names




250 mg*

Carisoprodol Tablets (C-IV)

Soma (C-IV)


350 mg*

Carisoprodol Tablets (C-IV)

Soma (C-IV)


* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Carisoprodol Combinations


Dosage Forms


Brand Names




200 mg with Aspirin 325 mg*

Carisoprodol and Aspirin Tablets (C-IV)

200 mg with Aspirin 325 mg and Codeine Phosphate 16 mg*

Carisoprodol, Aspirin and Codeine Phosphate Tablets (C-III)

AHFS DI Essentials™. © Copyright 2021, Selected Revisions February 24, 2020. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.


25. Drug efficacy study, Soma, Rela, Soma Compound, and Soma Compound with Codeine, National Academy of Sciences-National Research Council

27. BERGER FM, KLETZKIN M, LUDWIG BJ et al. Unusual muscle relaxant and analgesic properties of N-isopropyl-2-propyl-1,3-propanediol dicarbamate (carisoprodol). J Pharmacol Exp Ther. 1959; 127:66-74.

29. SCHWAB RS. MUSCLE RELAXANTS. Practitioner. 1964; 192:104-8.

100. Meda Pharmaceuticals Inc. Soma (carisoprodol) tablets prescribing information. Somerset, NJ; 2018 May.

101. Serfer GT, Wheeler WJ, Sacks HJ. Randomized, double-blind trial of carisoprodol 250 mg compared with placebo and carisoprodol 350 mg for the treatment of low back spasm. Curr Med Res Opin. 2010; 26:91-9.

102. Ralph L, Look M, Wheeler W et al. Double-blind, placebo-controlled trial of carisoprodol 250-mg tablets in the treatment of acute lower-back spasm. Curr Med Res Opin. 2008; 24:551-8.

103. See S, Ginzburg R. Skeletal muscle relaxants. Pharmacotherapy. 2008; 28:207-13.

104. van Tulder MW, Touray T, Furlan AD et al. Muscle relaxants for non-specific low back pain. Cochrane Database Syst Rev. 2003; :CD004252.

105. Roelofs PD, Deyo RA, Koes BW et al. Non-steroidal anti-inflammatory drugs for low back pain. Cochrane Database Syst Rev. 2008; :CD000396.

106. Chou R, Qaseem A, Snow V et al. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med. 2007; 147:478-91.

107. Institute for Clinical Systems Improvement. Health care guideline: adult acute and subacute low back pain 15th ed. Bloomington, MN; 2012 Jan. From the ICSI website

108. Toth PP, Urtis J. Commonly used muscle relaxant therapies for acute low back pain: a review of carisoprodol, cyclobenzaprine hydrochloride, and metaxalone. Clin Ther. 2004; 26:1355-67.

109. Watson Laboratories, Inc. Meprobamate tablets prescribing information. Corona, CA; 2004 Apr.

110. Nordeng H, Zahlsen K, Spigset O. Transfer of carisoprodol to breast milk. Ther Drug Monit. 2001; 23:298-300.

111. Briggs GG, Ambrose PJ, Nageotte MP et al. High-dose carisoprodol during pregnancy and lactation. Ann Pharmacother. 2008; 42:898-901.

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113. Reeves RR, Hammer JS, Pendarvis RO. Is the frequency of carisoprodol withdrawal syndrome increasing?. Pharmacotherapy. 2007; 27:1462-6.

114. Drug Enforcement Administration (DEA), Department of Justice. Schedules of controlled substances: placement of carisoprodol into schedule IV. 21 CFR Part 1308. Final Rule. [Docket No. DEA-333]. Fed Regist. 2011; 76: 77330-60.

115. Owens C, Pugmire B, Salness T et al. Abuse potential of carisprodol: a retrospective review of Idaho Medicaid pharmacy and medical claims data. Clin Ther. 2007; 29:2222-5.

116. Fass JA. Carisoprodol legal status and patterns of abuse. Ann Pharmacother. 2010; 44:1962-7.

117. Boothby LA, Doering PL, Hatton RC. Carisoprodol: a marginally effective skeletal muscle relaxant with serious abuse potential. Hosp Pharm. 2003; 38: 337-45.

118. US Department of Health and Human Services, Substance Abuse and Mental Health Services Administration (SAMHSA), Center for Behavioral Health Statistics and Quality. DAWN report: ED visits involving the muscle relaxant carisoprodol. 2011 Oct 27. From the SAMHSA website.

119. Gonzalez LA, Gatch MB, Taylor CM et al. Carisoprodol-mediated modulation of GABAA receptors: in vitro and in vivo studies. J Pharmacol Exp Ther. 2009; 329:827-37.

120. Dalén P, Alvan G, Wakelkamp M et al. Formation of meprobamate from carisoprodol is catalysed by CYP2C19. Pharmacogenetics. 1996; 6:387-94.

121. Simon S, D'Andrea C, Wheeler WJ et al. Bioavailability of oral carisoprodol 250 and 350 mg and metabolism to meprobamate: A single-dose crossover study. Curr Ther Res. 2010; 71: 50-9.

122. Reeves RR, Mack JE. Possible dangerous interaction of oxycontin and carisoprodol. Am Fam Physician. 2003; 67:2273.

123. . Carisoprodol, aspirin, and codeine phosphate tablets prescribing information. Princeton, NJ; 2018 Aug.

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209. Qaseem A, Wilt TJ, McLean RM et al. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. Ann Intern Med. 2017; 166:514-530.

210. Friedman BW, Cisewski D, Irizarry E et al. A Randomized, Double-Blind, Placebo-Controlled Trial of Naproxen With or Without Orphenadrine or Methocarbamol for Acute Low Back Pain. Ann Emerg Med. 2018; 71:348-356.e5.

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a. AHFS drug information 2020. Snow EK, ed. Carisoprodol. Bethesda, MD: American Society of Health-System Pharmacists; 2020.