Medications that act as central nervous system depressants and have sedative and musculoskeletal relaxant properties are called muscle relaxants. Used in addition to rest, physical therapy, and other measures to relieve discomfort, muscle relaxants are beneficial for short-term use for acute, painful musculoskeletal conditions.
The goal with these medications is a reduction of skeletal muscle spasms, relief of pain, and increased mobility of the affected muscles.
Muscle relaxants are not really a class of drugs, but rather a group of different drugs that each has an overall sedative effect.
Typically, muscle relaxants are prescribed early in a course of back pain, on a short-term basis, to relieve back pain associated with muscle spasms. Muscle relaxants are also sometimes prescribed for patients with back pain and other symptoms of fibromyalgia. It is thought that they may relieve the pain of tense muscles and muscle spasms common in fibromyalgia.
There are several types of muscle relaxant medications commonly used to treat back pain or neck pain.
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Common Muscle Relaxant Medications
Muscle relaxants usually used to treat back pain and other types of pain include:
Muscle tightness and muscle spasms, including those related to spine injuries, are eased with baclofen. The medication may be helpful in treating multiple sclerosis and stabbing nerve pain. It is available as a tablet and can be taken by children as young as 12 years old. Some common side effects could include nausea and vomiting, confusion, drowsiness, headache, or muscle weakness. Baclofen is rated C in the FDA’s A through X pregnancy safety ranking for medications, with A being the safest.
- Chlorzoxazone (Lorzone, Parafon Forte DSC)
Chlorzoxazone is used for the relief of discomfort from acute, painful, musculoskeletal conditions. It should not be used in patients with hypersensitivity to chlorzoxazone and rare liver toxicity has been reported. The doctor should be contacted in case of loss of appetite; nausea, vomiting, or tiredness; stomach pain; dark urine; pale stools; or yellowing of the skin or eyes. Chlorzoxazone is available as a tablet. It has not been rated by the FDA for safety during pregnancy.
- Carisoprodol (Soma)
Carisoprodol relaxes muscles and eases pain and stiffness caused by acute bone and muscle problems, as may be caused by an injury. It can be habit-forming, particularly if used in conjunction with alcohol or other drugs that have a sedative effect. Patients with a history of acute intermittent porphyria or hypersensitivity to carbamate medications such as methocarbamol should avoid carisoprodol. It is taken by mouth in tablet form and is also available in combination with aspirin or aspirin and codeine. It is rated C in the FDA’s pregnancy safety ranking for medications.
- Cyclobenzaprine (e.g. Amrix, Cyclobenzaprine Comfort Pac Fexmid, FlexePax, Flexeril, FusePaq Tabradol, Therabenzaprine-60)
Cyclobenzaprine eases stiffness and pain from muscle cramps, also called spasms. It is not advised for those with an overactive thyroid, heart rhythm problems, heart failure, or those who have had a heart attack recently. It can be used on a longer-term basis and has a chemical structure related to some antidepressant medications, although it is not an antidepressant. Cyclobenzaprine is not specifically approved for use in fibromyalgia, but is sometimes helpful in treating that condition. It is available as a tablet and extended-release capsule. Cyclobenzaprine is rated B by the FDA for safety during pregnancy, making it the safest of the muscle relaxants to use while pregnant.
- Dantrolene (Dantrium)
Dantrolene helps control chronic spasticity, including that related to spinal injuries. It is also used for conditions such as stroke, multiple sclerosis, and cerebral palsy. Dantrolene is taken as a capsule. It can cause liver problems, so the doctor may order regular blood tests to monitor the medication’s impact. Serious side effects are more likely in those with asthma, emphysema, bronchitis, or other lung diseases. It may cause sensitivity to light. Drowsiness is the most common side effect. The FDA has given dantrolene a C rating for safety in pregnancy.
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- Diazepam (e.g. Valium)
It addition to treating muscle spasms, diazepam relieves symptoms of anxiety and alcohol withdrawal and is used in seizure disorders such as epilepsy. Diazepam is usually limited to one to two weeks of use. This limitation is due to its habit-forming potential and because it alters sleep cycles, leading to sleep difficulties once the drug is stopped. Patients should also realize that diazepam is a depressant and can worsen depression associated with chronic pain. Diazepam is not advised for those who are pregnant (it is rated D by the FDA for safety during pregnancy), have myasthenia gravis, severe liver disease, sleep apnea (oral tablet only), serious breathing troubles, or some forms of glaucoma. It is sold as a tablet, liquid, injection, and a rectal gel.
- Metaxalone (e.g. Skelaxin, Metaxall)
Metaxalone targets pain and muscle spasms from sprains, strains, and muscle injuries. Metaxalone is the least likely of the muscle relaxers to cause sleepiness. It can be used in children 13 and older for musculoskeletal conditions, but it has not been rated for safety during pregnancy. The medication is not safe for people with a known tendency to drug-induced, hemolytic, or other anemias, and kidney or liver disease. Metaxalone may affect blood sugar tests for people with diabetes. It is available as a tablet or injection.
- Methocarbamol (e.g. Robaxin, Robaxin-750)
Methocarbamol eases acute muscle pain. It is classified as a carbamate and can also be used as an adjunct therapy to control the neuromuscular manifestations of tetanus, though it does not treat tetanus. It can be taken by as a tablet or by injection. Higher doses are sometimes given the first 48 to 72 hours of treatment. Those who have had an allergic reaction to any related medication should avoid methocarbamol. It is in pregnancy category C.
- Tizanidine (e.g. Comfort Pac with Tizanidine, Zanaflex, Zanaflex capsule)
Muscle spasticity is managed by tizanidine, and is typically reserved for daily activities and times when relief of spasticity is most important. It is used in adults with multiple sclerosis and spinal cord injury and in children with cerebral palsy. It should not be used with patients taking fluvoxamine or ciprofloxacin or those who have liver disease. Those who have experienced an allergic reaction to tizanidine should also avoid tizanidine. It is available in tablet and capsule form which absorb differently when taken with food. Tizanidine is in pregnancy category C.
Sometimes the first muscle relaxant a doctor prescribes does not work as well as expected. It may be necessary to try an alternative if the initial prescription is not effective.
There is very little research regarding which type of muscle relaxant is more effective, so the choice of which medication—or whether to use one at all—is based more on factors such as the patient's reaction to the medication and personal preferences, potential for abuse, possible drug interactions, and adverse side effects.
Medication is just one part of pain relief. These medications are intended to be one element, usually on a short-term basis, of an overall recovery strategy that goes beyond medication to include rest, stretching, physical therapy, and other exercise.