Muscle relaxers are a group of drugs used to treat musculoskeletal pain, meaning pain involving muscles, bones, joints, and connective tissues like ligaments and tendons. Muscle relaxers are sometimes prescribed to people with osteoarthritis (“wear-and-tear” arthritis) as well as those with lower back pain, neck pain, and other musculoskeletal pain.
This article explains how muscle relaxers work, when they are used, and which types are available for people with osteoarthritis and other types of musculoskeletal pain. It also describes the possible risks and side effects of muscle relaxers, including when they should not be used.
How Muscle Relaxers Work
Muscle relaxers, also known as muscle relaxants, are a group of drugs with sedative properties. While people tend to think of sedatives as “sleeping pills,” the types used as muscle relaxers prevent nerve signals or pain impulses from reaching the brain. This action helps relieve muscle spasms and tension that contribute to musculoskeletal pain.
Different types of drugs are used as muscle relaxers. While they all have similar mechanisms of action (in that directly act on the central nervous system), they have different chemical structures and indications for use. Some have stronger sedative effects than others, while others are used to treat specific medical conditions (for example, injuries or diseases of the spinal cord).
Muscle relaxers can be broadly categorized as follows:
- Benzodiazepines: These are central nervous system depressants typically prescribed to treat anxiety, insomnia, and seizures. The types used for pain are short-acting.
- Skeletal muscle relaxants: These are a group of drugs that block pain impulses to the brain (neuromuscular blockers) and/or relieve muscle spasms (spasmolytics).
When Muscle Relaxers Are Used
As a general rule, muscle relaxers are used for the short-term treatment of musculoskeletal pain. They can be used “on demand” when acute pain strikes but are generally not the drugs of choice for chronic musculoskeletal pain.
There is limited research as to which muscle relaxers work “better” than others. Finding the right one often involves a process of trial and error. In the end, the choice is largely based on personal preference, possible side effects, and the potential for abuse and drug dependence.
Furthermore, muscle relaxers are usually not used for the primary treatment of pain. More often, they are prescribed when other more conservative treatments, like over-the-counter (OTC) nonsteroidal anti-inflammatory drugs (NSAIDs), fail to provide relief.
Muscle relaxers may be prescribed for people with the following conditions:
- Osteoarthritis pain
- Lower back pain
- Neck pain
- Sprains or strains of muscles, ligaments, or tendons
- Tension headaches
- Fibromyalgia
- Spinal injuries
- Myofascial pain syndrome
- Temporomandibular joint (TMJ) dysfunction
- Multiple sclerosis
Some muscle relaxants cause greater drowsiness than others, especially certain benzodiazepines. This can be useful if the pain is interfering with your sleep.
List of Common Muscle Relaxers
Muscle relaxers are available by prescription. There are no OTC muscle relaxers. Many are prescribed in tablet, capsule, or liquid form, but there are also injectable forms used for rapid relief of acute pain.
Some of the more commonly prescribed muscle relaxants (by class) include:
Possible Side Effects and Risks
As with all drugs, muscle relaxers can cause side effects. The one possible side effect common to all muscle relaxers is dizziness and drowsiness, although some cause greater drowsiness than others.
Common side effects of muscle relaxants (by drug class) include:
Certain muscle relaxers pose a major risk of drug dependence. Among those known to be habit-forming are Amrix, Ativan, Restoril, Soma, and Valium. It is for this reason that these drugs are generally not prescribed for longer than four weeks when used for acute musculoskeletal pain.
Drowsiness
Dizziness or lightheadedness
Restlessness
Nausea or vomiting
Headache
Slurred speech
Muscle weakness
Tremors
Loss of coordination
Blurred vision
Constipation
Confusion
Reduced sex drive
Headache
Dry mouth
Dizziness
Drowsiness
Stomach upset
Fatigue
Loss of appetite
Muscle weakness
Diarrhea
Constipation
Blurred vision
The risk of dependence is increased when benzodiazepines are prescribed alongside opioid drugs like fentanyl.
Meanwhile, skeletal muscle relaxers like Dantrium, Flexeril, Lorzone, Robaxin, Skelaxin, Soma, and Zanaflex may need to be used with caution in people with preexisting liver or kidney disease. In some cases, the drugs may need to be avoided entirely.
Benzodiazepines are avoided during pregnancy.
Summary
Muscle relaxers are sometimes prescribed for people with osteoarthritis pain and other types of musculoskeletal pain. They are available by prescription only and intended for short-term use.
Drinking alcohol can be especially dangerous when taking muscle relaxers. Alcohol increases the sedative effects of the drugs and, in some cases, can lead to severe respiratory depression and death.
There are two broad categories of muscle relaxers (benzodiazepines and skeletal muscle relaxants), each of which acts on the nervous system in different ways. The drugs are usually not prescribed as the primary treatment of musculoskeletal pain but are rather reserved for when conservative treatments fail to provide relief.
A Word From Verywell
Muscle relaxers can be very effective for the treatment of severe muscle, joint, back, or neck pain. With that said, they are not intended for long-term use and should only be taken as prescribed.
If pain persists despite the appropriate use of muscle relaxants, speak with your healthcare provider. Other treatments may be available, like nerve blocks or radiofrequency ablation, that may not only be safer over the long term but provide more effective, sustained relief.
- Cashin AG, Folly T, Bagg MK, et al. Efficacy, acceptability, and safety of muscle relaxants for adults with non-specific low back pain: systematic review and meta-analysis. BMJ. 2021;374:n1446. doi:10.1136/bmj.n1446
- Wright SL. Limited utility for benzodiazepines in chronic pain management: a narrative review. Adv Ther. 2020;37(6):2604–19. doi:10.1007/s12325-020-01354-6
- Witenko C, Moorman-Li R, Motycka C, et al. Considerations for the appropriate use of skeletal muscle relaxants for the management of acute low back pain. P T. 2014 Jun;39(6):427-35.
- Park TW, Saitz R, Nelson KP, Xuan Z, Liebschutz JM, Lasser KE. The association between benzodiazepine prescription and aberrant drug-related behaviors in primary care patients receiving opioids for chronic pain. Subst Abus. 2016 Oct-Dec;37(4):516–20. doi:10.1080/08897077.2016.1179242
By Carol Eustice
Carol Eustice is a writer covering arthritis and chronic illness, who herself has been diagnosed with both rheumatoid arthritis and osteoarthritis.
