Muscle Relaxers & Drug Abuse

Muscle relaxers or relaxants are medications with sedative and depressant properties used to treat a wide array of musculoskeletal conditions. Typically prescribed in combination with physical therapy, the goal of these medications is to reduce skeletal muscle spasms, alleviate pain and increase mobility of impacted muscles. In addition, many of these drugs are prescribed for fibromyalgia and back pain. Studies have not demonstrated the superiority of these drugs to acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) for low back pain. Systematic reviews and meta-analyses support their use for short-term relief of acute low back pain when nonprescription drugs are poorly tolerated or ineffective. The American Pain Society and the American College of Physicians recommend using acetaminophen and NSAIDs as first-line agents for acute low back pain and reserving skeletal muscle relaxants as an alternative therapy.

Types of Muscle Relaxers

Prescription muscle relaxants are classified into two basic types. Antispasmodics are centrally acting skeletal muscle relaxants (SMRs) and antispastics are drugs that only suppress muscle spasms. Experts theorize antispasmodics help alleviate muscle spasms and associated pain through their sedative properties and/or by preventing nerves from sending pain signals to the brain. Antispastics are typically prescribed for conditions that cause muscle spasticity, including brain injuries, spinal cord injury and multiple sclerosis. Spasticity is clinically defined as “a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon reflexes, resulting from excitability of the stretch reflex.” In lay terms, spasticity is a problem involving excessive permanent increase in muscle tone when a person is at rest.

Muscle Relaxer Names

Perhaps you’re familiar with some of the most common and widely prescribed names of muscle relaxers, such as Valium (diazepam), Soma (carisoprodol) or Flexeril (cyclobenzaprine). These are just a few of the many muscle relaxants available by prescription. Below is a brief description of the most common muscle relaxants, categorized by type, with brand and generic names.


Soma (carisoprodol): Physical or psychological dependence is possible with potential withdrawal symptoms after discontinuation. Carisoprodol was found to be superior to diazepam for the short-term treatment of moderately severe low back pain and spasm. Carisoprodol should only be used for short periods (2-3 weeks) due to lack of evidence proving effectiveness with longer use. This drug may cause drowsiness and dizziness, and should not be used in anyone aged 65 and older.

Parafon Forte, Lorzone (chlorzoxazone): This drug acts primarily at the level of the spinal cord and subcortical areas of the brain, where it inhibits reflexes involved in skeletal muscle spasms. The side effects are similar to most muscle relaxants, with the exception of a limited number of reported cases of significant hepatotoxicity. Therefore, it is not recommended for anyone with liver problems.

Fexmid, Flexeril, Amrix (cyclobenzaprine)

This drug is the most widely studied and has been shown to be effective for muscle stiffness and pain. Structurally similar to tricyclic antidepressants, it is believed to impart analgesic effects by interfering with serotonin transmission at the spinal cord. The recommended dose of cyclobenzaprine is 5 or 10 mg three times daily for immediate release tablets or 15 or 30 mg once daily for extended release tablets. As with most drugs, it is possible to overdose on Flexeril. Combining cyclobenzaprine with opioid analgesics or antidepressant medication increases the risk of neuropsychiatric side effects such as psychosis and delirium, as well as spasmodic muscle contractions.

Skelaxin, Metaxall (metaxalone)

Typically well tolerated, this drug is a used in addition to rest, physical therapy and other measures for relief of discomfort associated with acute and painful musculoskeletal conditions. It is commonly prescribed as a muscle relaxant, although it has no direct muscle relaxant effects. Metaxalone overdose can lead to potentially deadly serotonin syndrome, as evidenced by case studies, however, both subjects ingested other medications and one intentionally attempted suicide.

Robaxin (methocarbamol)

An inexpensive and less sedating option than cyclobenzaprine or carisoprodol, this drug has shown efficacy for low back pain. In a recent study, 44% of people achieved complete low back pain relief. Robaxin methocarbamol tablets are a carbamate derivative of guaifenesin, a CNS depressant with sedative and musculoskeletal relaxant properties.

Norflex (orphenadrine)

This drug works by blocking nerve impulses or pain sensations sent to the brain. It is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.

Zanaflex (tizanidine)

Tizanidine is indicated for the symptomatic treatment of painful muscle spasms due to musculoskeletal disorders and at higher doses for disease-specific spasticity. It is used in adults with multiple sclerosis and spinal cord injury and in children with cerebral palsy. In combination with NSAIDs, it is superior to NSAIDs alone. A 2009 study found it was superior to aceclofenac monotherapy for the treatment of acute low back pain. It should not be used by individuals with liver disease or with the drugs fluvoxamine or ciprofloxacin.


Lioresal, Gablofen, Lioresal (baclofen): Baclofen is chemically related to gamma-aminobutyric acid (GABA), a naturally occurring neurotransmitter in the brain. GABA released by some nerves results in decreased activity of other nerves. It is believed the GABA-like action of baclofen blocks the activity of nerves within the part of the brain controlling the contraction and relaxation of skeletal muscles.

Dantrium (dantrolene)

This drug helps control chronic spasticity related to spinal injuries, stroke, multiple sclerosis and cerebral palsy. Dantrolene is taken as a capsule and can cause liver problems, so regular blood tests are typically required to monitor liver health. Individuals with asthma, emphysema, bronchitis or other lung diseases are more likely to experience serious side effects.

Valium (diazepam)

A benzodiazepine used to treat anxiety, muscle spasms, seizures, insomnia, epilepsy and some effects of alcohol withdrawal, Valium was introduced in 1963 and quickly gained popularity for its sedative effects. Between 1969 and 1982, Valium was the most prescribed drug in the U.S., viewed by clinicians as a worry-free panacea. In 1979, sales reached a peak with more than 2.3 billion pills sold. Diazepam has similar sedative and hypnotic effects as barbiturates, however, it is far less likely to result in lethal overdose and thought to have less abuse potential than newer benzos like Xanax. Although the peak of Valium abuse was decades ago, accounts of epidemic abuse periodically resurface and the drug continues to be sold on the black market. Valium should not be taken with any prescription opioids due to the increased risk of fatal overdose.

Side Effects of Muscle Relaxers

The side effects of muscle relaxers vary somewhat based on the medication and individual. Serious side effects include breathing problems, lightheadedness or fainting, blurred vision, confusion, nausea and urinary retention. The most common side effects of antispasmodics include:

  • Constipation
  • Drowsiness
  • Dizziness
  • Dry mouth
  • Fatigue
  • Headache
  • Nervousness
  • Reddish-purple or orange urine
  • Lowered blood pressure upon standing

The most common side effects of antispastics include:

  • Drowsiness
  • Dizziness
  • Weakness
  • Fatigue

Special Precautions

Muscle relaxants should not be combined with antihistamines, St. John’s wort or sleep medications. The excessive sedative effect when taken with other central nervous system depressants such as alcohol, opioids, benzodiazepines or barbiturates can result in respiratory depression and death. Dosing timing is important because a muscle relaxant designed to last 12 hours taken at 10 pm can cause impaired driving before 10 am. Gradual tapering off of these drugs is recommend because withdrawal symptoms such as seizures or hallucinations can occur.

Abuse of Muscle Relaxers

Muscle relaxers are prescribed on a short-term basis because they have the potential to be addictive and in that event, require specialized SOMA addiction treatment. Carisoprodol and diazepam are both classified by the U.S. Drug Enforcement Administration as Schedule IV controlled substances due to their potential for abuse and addiction, as evidenced by studies. Literature also suggests abuse potential for baclofen, methocarbamol, orphenadrine and tizanidine, although relatively few animal and human studies have been conducted.

Carisoprodol was originally thought to have a lower potential for abuse and addiction than other muscle-relaxing drugs used in the 1950s-60s. More recent evidence shows it is habit forming, especially when taken in combination with other drugs. In a person who readily metabolizes carisoprodol, large amounts result in a sedative-hypnotic effect that may lead to psychological addiction. The drug intensifies the effects of Xanax, creating a potentially lethal duo when taken together. This drug is intentionally abused to enhance the effectiveness of other drugs, with users creating “cocktails” to simulate the effects of narcotic substances including heroin. Back in 2000, the Drug Abuse Warning Network listed carisoprodol as the 20th most abused drug, ranking higher than oxycodone and methadone.

Abusing any of these muscle relaxers can increase the risk and severity of side effects and possibly lead to dependence. Only use these medications short-term as recommended, and follow all precautions. Don’t abruptly stop taking these drugs and seek professional help if you feel you have become addicted.

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