When people endure back, neck, or other musculoskeletal pain, they tend to reach for over-the-counter painkillers. When those fail to provide relief, their doctors might prescribe a different and less-familiar type of drug known as a muscle relaxer. That can lead to questions, including what do muscle relaxers do? Are muscle relaxers addictive? And are there over-the-counter muscle relaxers so I can skip the trip to the doctor?
Bottom Line Health asked Cleveland Clinic physiatrist Geraldine P. Dapul, MD, what patients need to know.
What do muscle relaxers do?
What these drugs do depends on which type is prescribed. There are two main classes of muscle relaxers—antispasmodics and antispastics. Antispasmodics are used to treat muscle spasms, while antispastics are used to treat muscle spasticity. The terms spasms and spasticity sound similar and both involve involuntary muscle contractions, but these are different symptoms that are caused by different medical issues, and they’re generally treated with different muscle relaxers.
Muscle spasms typically involve potentially painful cramping and can be caused by a range of activities and conditions. Muscles might spasm following intense exercise, for example, or due to dehydration. Muscle spasms often quickly pass without the help of medication, or with nothing more than an over-the-counter painkiller, but when the spasms persist for more than a couple days and the pain is substantial, an antispasmodic muscle relaxer could be appropriate. Example: A muscle relaxer might be prescribed to help a patient cope with lower back or neck pain following a car accident.
The most commonly prescribed antispasmodic muscle relaxer is cyclobenzaprine, which is sold under brand names including Fexmid and Flexeril. Other antispasmodic muscle relaxers include carisoprodol, chlorzoxazone, metaxalone, methocarbamol, and orphenadrine. These drugs should not be considered a first line of defense against musculoskeletal pain: They’re appropriate only if muscle pain does not improve after two to three days of over-the-counter pain medications combined with taking it easy on the painful body part.
They also tend to be a poor choice for chronic pain. Long-term use of these drugs can have serious side effects, including liver damage, kidney damage, or addiction. They’re most appropriate when approximately seven to 10 days of pain relief is needed following a significant musculoskeletal injury.
If the pain persists longer than that, and antispasmodic muscle relaxer use drags on past two to three weeks, it’s worth wondering whether these drugs are truly helping. Perhaps the pain is being caused by something other than muscle pain, or perhaps the patient has developed a tolerance to these drugs, reducing their effectiveness, which can occur with extended use.
In these situations, patients and their doctors should seek alternative solutions, perhaps including physical therapy. When muscle relaxers are used for more than a couple weeks, doctors often order lab tests to monitor liver and kidney function and ensure the extended use of this medication isn’t damaging these organs.
The most common side effect of antispasmodic muscle relaxers is drowsiness. Dizziness and lightheadedness are relatively common, too, and some patients experience a drop in blood pressure, headaches, upset stomachs, or other side effects. As noted above, there also is the potential for liver and kidney complications. Do not drink alcohol while on these drugs: Alcohol and these muscle relaxers can combine to have an even greater sedative effect.
Other antispasmodic muscle relaxers, including dicyclomine, hyoscine, and hyoscyamine, sometimes are prescribed to treat abdominal pain stemming from the cramping and spasms of muscles involved in digestion. For example, they might be prescribed for patients suffering from irritable bowel syndrome.
Muscle spasticity is caused by an issue affecting the brain or spinal cord’s control over muscles, not by damage to muscles themselves. The consequences can include muscle spasms and/or extended involuntary muscle contractions that make muscles seem frozen in position. Conditions that can lead to spasticity include traumatic brain or spinal cord injury, stroke, multiple sclerosis, cerebral palsy or amyotrophic lateral sclerosis.
Antispastic muscle relaxers that might be prescribed to patients with conditions such as these include baclofen, tizanidine, dantrolene, and diazepam. As with the antispasmodic muscle relaxers described above, the most common side effect is sedation—and, as above, alcohol consumption should be avoided while taking them. Other potential side effects vary by drug, but might include lowered blood pressure, headache, or constipation. Unlike antispasmodic muscle relaxers, these antispastic muscle relaxers are prescribed for long-term medical conditions, which means these drugs often used for much longer than a couple weeks. Warning: Diazepam can be addictive. It’s better known by the brand name it’s sold under—Valium.
Over-the-counter isn’t an option
There are no over-the-counter muscle relaxers in the United States. Misuse and overuse of these drugs can have serious side effects, in some cases including addiction, so it is not appropriate for patients to use them without medical oversight.
You might encounter over-the-counter products that include terms such as “muscle relax” or “muscle relaxant” in their names, but these likely are herbal remedies or vitamin pills unrelated to the prescription muscle relaxers discussed above.
