The Problem with Muscle Relaxants

The problem with muscle relaxants — and it’s a big problem — is this: Although the drugs are effective and have been in use for decades, they appear to work by causing general nervous system sedation and not by targeting muscle tissue.

You might say: “who cares as long as they work.” That’s a legitimate perspective — the precise mechanism of action of many drugs is not known. And muscle pulls and spasms — especially in the neck and/or back — can be painful, limiting range of motion and disrupting sleep and normal activities for days. I’ve had them, and on occasion, yes, I’ve resorted to muscle relaxants.

I would argue, however, that muscle relaxants deserve to be prescribed and taken with much more caution than they are. They are widely prescribed because, of course, muscle pulls and strains, and back pain in general, are nearly ubiquitous maladies.

In addition, many of the available studies on muscle relaxants are old and don’t meet today’s standards for high-quality research. Thus, the continued widespread use of muscle relaxants isn’t backed up by recent research showing the balance of benefits versus risks.

And Then There’s the Abuse

There’s also the problem of abuse. A 2014 report from Express Scripts, the giant pharmacy benefit manager, found that 30 percent of people taking a prescription opioid painkiller in 2013 were also taking an anti-anxiety drug or a muscle relaxant; 8 percent had taken all 3 in the timeframe studied. That’s not good.

The advice and tables below derive primarily from a Consumer Reports Best Buy Drugs report on muscle relaxants. (This is a pdf summary of the findings.) This 2015 report is based on a systematic review of 120 studies by a team of physicians and researchers at the Oregon Health & Science University Evidence-Based Practice Center. The report also took into account recent reviews of muscle relaxants by the Cochrane Collaborative and treatment guidelines from the American College of Physicians and the American Pain Society.

Try Other Approaches First

If you’ve strained or pulled a muscle, have muscle spasms, or fall prey to back or neck pain that’s mild to moderate in intensity, try non-drug approaches first to ease the pain. These include use of a heating pad, judicious stretching and mild exercise, relaxation and deep breathing, saunas and hot tubs, massage, and yoga. While there’s little rigorous research proving these approaches work, anecdotal experience plus evidence from many small studies support their benefit.

Talk with your doctor about the balance between resting the affected area and light exercise and activity. Evidence these days suggests that becoming a couch potato after a muscle injury — as long as the damage is not severe — is often the worst thing to do. Light exercise and stretching promote healing.

Over-the-Counter Pain Relievers

You’ll likely reach for one, and there’s nothing wrong with that — for most people. Indeed, if the injury is moderate to severe, and thus more painful, taking the OTC pain reliever of your choice is advisable. There’s no good evidence on which drug works best for muscle injuries and pulls, although many doctors recommend NSAIDs (non-steroidal anti-inflammatory such as ibuprofen/Advil or naproxen/Aleve) rather than acetaminophen (Tylenol) because of their anti-inflammatory effects.

Studies don’t find any benefit of adding a muscle relaxant to the mix if you are getting acceptable relief from non-drug approaches and OTC pain relievers. In one recent follow-up study of 323 people showing up at an emergency room with low back pain, for example, neither an NSAID plus a drug containing oxycodone and acetaminophen, or an NSAID combined with the muscle relaxant cyclobenzaprine (Flexiril) provided better pain relief or improved function than an NSAID (naproxen) alone. The patients were assessed at 7 days and again 3 months after the emergency room visit. (JAMA, Oct 20, 2015)

When a Muscle Relaxant Might Be Needed

Some people with a muscle pull, spasms or injury, or backache may need to take a muscle relaxant. They are:

  • People with liver, kidney or heart disease of any kind, glaucoma, or stomach ulcers who can’t take either an acetaminophen or NSAIDs, or both, and for whom a muscle relaxant may be preferable to an opioid painkiller.
  • People who don’t get sufficient pain relief from over-the-counter drugs. Pain is a subjective experience and some people are very pain sensitive.
  • People whose pain or discomfort prevents them from sleeping. The sedation associated with muscle relaxants will be viewed as desirable when the drug is taken at night.

Side Effects

Muscle relaxants cause a range of side effects that, as suggested above, warrant care when taking one. Everyone who takes a muscle relaxant experiences one or more of these effects, and many experience all:

  • Sedation/drowsiness/sleepy
  • Fatigue
  • Body weakness
  • Dizziness or light-headedness
  • Dry mouth
  • Depressed mood
  • Lowered blood pressure


The biggest practical problem is that people take muscle relaxants and expect to be able to function and work normally, including driving, operating machinery or doing cognitive tasks that require focus. As with opioids, muscle relaxants make all those tasks harder, even at low doses. And doing them while taking a muscle relaxant presents real risks of harm due to falls and accidents The package warnings that accompany the drugs warn against driving or operating heavy machinery. You may think you can ignore that, but you shouldn’t.

Drinking is also discouraged while taking a muscle relaxant. This advice, too, is routinely ignored and shouldn’t be unless it’s a drink at home before bedtime. Combining the two exacerbates, exponentially, poor functionality and mental acuity.


Muscle relaxants are not recommended for people 65 years or older — at all. There are 2 reasons for this. First, the sedating effects of the drugs are more likely to be more intense in older people, who are already at higher risk of falls and home or workplace accidents. Second, many people aged 65 and older take other medicines that could interact with muscle relaxants in adverse ways — again enhancing the risk of falls or other accidents.

Muscle relaxants are also not recommended for pregnant women, and people with a history of depression or substance abuse problems.

Although most of the existing research doesn’t show any clear differences between the various muscle relaxants in the risk of different side effects they pose, the Best Buy Drug report calls out two of the drugs for specific problems.

Carisoprodol (Soma) has been associated with a high risk of abuse and addiction potential, though there’s as yet no clear understanding of the magnitude of this additional risk. Carisoprodol is the only muscle relaxant that’s classified as a controlled substance, primarily due to the high number of reports of emergency visits attributable to the drug by the Drug Abuse Network.

Chlorzoxazone (Lorzone) has been associated with serious liver damage, although the incidence is rare. Even so, the drug should not be prescribed at all for people with liver disease or hepatitis.

Abuse of cyclobenzaprine (Flexiril) is also on the rise. From 2004 to 2010, for example, there was a 100 percent increase in the number of emergency room visits associated with the drug. That’s likely because it’s among the most prescribed muscle relaxants and because abuse of all psychoactive drugs has increased in the last decade.

Selected Muscle Relaxants: Key Things to Know

Cyclobenzaprine (Flexeril)

  • Effectiveness supported by strongest body of evidence.
  • 5 mg as effective as 10 mg, with fewer side effects.
  • Should not be used by people with heart disease, arrhythmias, or glaucoma.

Cyclobenzaprine (Amrix)

  • Sustained-release formulation allows for once daily dosing.
  • Not found to be more effective than standard-release formulation
  • No generic available.
  • Should not be used by people with heart disease, arrhythmias, or glaucoma.

Carisoprodol (Soma)

  • Metabolized to meprobamate, a drug classified as a controlled substance because of abuse and addiction potential.
  • Case reports of abuse and addiction.
  • Avoid using the drug due to risk of addiction.

Chlorzoxazone (Lorzone)

    • Rare cases of liver toxicity.
    • May cause red-orange urine but this is not harmful.

Metaxalone (Skelaxin)

      • Should not be used by people with liver damage or kidney disease.

Methocarbamol (Robaxin, Robaxin-750)

      • May cause black, blue, or green urine, but this is not harmful.
      • Should not be used by people with liver disease.

Orphenadrine (Generic only)

    • Should not be used by people with liver disease, heart disease, arrhythmias, or glaucoma.

Source: Consumer Reports Best Buy Drugs

The Bottom Line

Avoid taking a muscle relaxant if nondrug approaches or OTC drugs reduce your discomfort and pain. If you have to take one, tell your doctor about all the other drugs you’re taking, take the muscle relaxants with great care, at the lowest dose possible, and preferably at night. Don’t take it for long — at most 10 days. There’s little evidence to show that long-term use improves symptoms.

If you have muscle spasms or back pain that does not resolve in a week or so, or flares up from time to time, see a specialist. Taking muscle relaxants has not been shown effective in the long-term treatment of back pain. Neither have opioid painkillers.

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