Other side effects include: dizziness, clumsiness, headache, fast heart rate, upset stomach, vomiting and skin rash.

[13] The interaction of carisoprodol with essentially all opioids, and other centrally acting analgesics, but especially codeine, those of the codeine-derived subgroup of the semisynthetic class (ethylmorphine, dihydrocodeine, hydrocodone, oxycodone, nicocodeine, benzylmorphine, the various acetylated codeine derivatives including acetyldihydrocodeine, dihydroisocodeine, nicodicodeine and others) which allows the use of a smaller dose of the opioid to have a given effect, is useful in general and especially where skeletal muscle injury and/or spasm is a large part of the problem.

[24] Carisoprodol, meprobamate, and related drugs such as tybamate, have the potential to produce physical dependence of the barbiturate type following periods of prolonged use.

It may reach clinical significance before physiological tolerance and dependence have occurred and (as with benzodiazepines) has been demonstrated to persist to varying degrees of severity for months or years after discontinuation.

Discontinuation of carisoprodol, as with all GABA-ergics, can result in cognitive changes which persist for weeks, months, or rarely even years including greatly increased anxiety and depression, social withdrawal, hair-trigger agitation/aggression, chronic insomnia, new or aggravated (often illogical) phobias, reduced IQ, short term and long-term memory loss, and dozens of other sequelae.

[26] The effects, severity, and duration appear to be slightly dose-dependent but are mainly determined by the patients pattern of use (taken as prescribed, taken in bulk doses, mixed with other drugs, a combination of the above, etc.

Psychotherapy and cognitive behavioral therapy have demonstrated moderate success in reducing the rebound anxiety which results upon carisoprodol discontinuation but only when combined with regular and active attendance to a substance use support group.

Combining a muscle relaxant like carisoprodol with opioids and benzodiazepines is referred to as "The Holy Trinity" as it has been reported to increase the power of the "high".

On 26 March 2010 the DEA issued a Notice of Hearing on proposed rule making in respect to the placement of carisoprodol in schedule IV of the Controlled Substances Act.

[32] Overdose symptoms are similar to those of other GABAergics including excessive sedation and unresponsiveness to stimuli, severe ataxia, amnesia, confusion, agitation, intoxication and inappropriate (potentially violent) behavior.

Treatment mirrors that of barbiturate overdoses and is generally supportive, including the administration of mechanical respiration and pressors as indicated and, in rare cases, bemegride.

[citation needed] In 2014 actress Skye McCole Bartusiak died of an overdose due to the combined effects of carisoprodol, hydrocodone and difluoroethane.

[34] In 1999 actress Dana Plato died after taking carisoprodol (Soma) along with a few doses of a hydrocodone / acetaminophen painkiller (Lortab), in an overdose that was ruled a suicide.

In June 1959, several American pharmacologists convened at Wayne State University in Detroit, Michigan to discuss a newly discovered structural analogue of meprobamate.

[38] Building on meprobamate's pharmacological effects, carisoprodol was intended to have better muscle relaxing properties, less potential for addiction, and a lower risk of overdose.

[41] In the EU, the European Medicines Agency issued a release recommending member states suspend marketing authorization for this product in the treatment of acute (not chronic) back pain.

[43] In December 2011, the Drug Enforcement Administration (DEA) issued the final ruling placing carisoprodol on Schedule IV of the Controlled Substances Act (CSA).