How Does Methocarbamol Work? All About Its Mechanism of Action
Key takeaways:
Methocarbamol is a medication that treats muscle-related pain. Its mechanism of action isn’t fully understood.
It likely works in the brain to relax the nerves that usually turn on your muscles. It may also directly block sodium channels in muscles, causing them to stay relaxed longer.
Methocarbamol isn’t usually a first-choice treatment option for short-term muscle pain. Non-medication options, including physical therapy, rest, and heat application, are typically tried first.
Methocarbamol is less likely to cause drowsiness than some other muscle relaxers. But it still can cause drowsiness and other side effects, so it isn’t usually recommended if you’re 65 or older.
Table of contents
If you’ve ever experienced muscle pain, you may have been prescribed a muscle relaxer. Methocarbamol is one type of muscle relaxer that treats short-term muscle pain. How it works isn’t entirely understood. But here we’ll cover what we do know about methocarbamol’s mechanism of action and whether it’s a good option for treating muscle pain.
What is methocarbamol?
Methocarbamol is part of a group of medications called muscle relaxers. These medications are used to treat muscle-related pain.
Methocarbamol is FDA approved to treat short-term muscle pain from musculoskeletal conditions. These are conditions where you may have pain or a loss of function in your muscles. Examples include chronic low back pain, osteoarthritis, and rheumatoid arthritis.
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Methocarbamol is available as 500 mg and 750 mg tablets. It’s usually taken 3 or 4 times a day and is meant to be used along with physical therapy, rest, and other pain relief strategies. It’s not usually intended for long-term use, so ask your prescriber how long they expect you to take it.
How does methocarbamol work?
Though methocarbamol’s mechanism of action isn’t fully understood, it’s thought to ease muscle pain by relaxing skeletal muscles.
Skeletal muscles are one of three types of muscles in the body (the other two are heart muscle and smooth muscle). Skeletal muscles are attached to your bones. They allow your body to move by tightening (contracting) and relaxing.
For a long time, it was thought that methocarbamol didn’t directly affect your muscles. Instead, it was believed to work within the brain and spinal cord to relax certain nerves that typically activate (turn on) your muscles. In turn, this reduces muscle contractions to help relax your muscles and relieve pain.
But more recently, there’s some evidence that methocarbamol does affect muscles directly. It’s possible that methocarbamol affects sodium channels in the muscles. This causes your muscles to stay relaxed for longer than they would otherwise. But this effect was found in an animal study, so we need human studies to know for sure.
Does methocarbamol begin to work immediately?
Methocarbamol starts to work in about 30 minutes. You’ll know it’s working if you feel improvement in your muscle-related symptoms, like muscle pain and discomfort.
Is methocarbamol a first-choice option for muscle pain?
Not usually. Typically, non-medication options are recommended before trying medications for muscle pain. Some possible options include:
Physical therapy and exercises that can relieve back and neck pain
Massage therapy
Applying heat to your muscles
If non-medication options don’t work, your prescriber may recommend over-the-counter (OTC) medications next. OTC nonsteroidal anti-inflammatory drugs (NSAIDs) can be used to help manage muscle pain. Examples include ibuprofen (Advil, Motrin) and naproxen (Aleve). Prescription NSAIDs like meloxicam (Mobic) or muscle relaxers may also be an option. Sometimes, an NSAID and a muscle relaxer like methocarbamol are even combined.
For short-term muscle pain that isn’t in the lower back, guidelines don’t recommend skeletal muscle relaxants. If medications are needed, topical (applied to the skin) NSAIDs like diclofenac (Voltaren Arthritis Pain) with or without menthol are recommended. Oral NSAIDs may be used as well.
Good to know: If you’re over 65 years old, muscle relaxers aren’t recommended. This is because they can cause drowsiness and anticholinergic side effects, which may be worse in people who are older than 65. This increases your risk of falls and injuries.
What other muscle relaxers are available besides methocarbamol?
The best muscle relaxer for you depends on what you’re treating, your health history, and what other medications you take. There are many muscle relaxers on the market, including:
Baclofen (Fleqsuvy, Lyvispah, Ozobax DS)
Cyclobenzaprine
Dantrolene (Dantrium)
Carisoprodol (Soma)
Tizanidine (Zanaflex)
Metaxalone
Diazepam (Valium)
These medications are divided into two categories: antispastics and antispasmodics. Antispastic medications include baclofen and dantrolene. They’re used for conditions like multiple sclerosis to treat muscle spasms due to brain or spinal cord damage.
The others listed here, including methocarbamol, are antispasmodic medications. They treat skeletal muscle-related pain. Tizanidine and diazepam have both antispastic and antispasmodic properties.
As mentioned, muscle relaxers aren’t a first-choice treatment option for muscle-related pain. But if your prescriber thinks a muscle relaxer would help you, methocarbamol may be an option. It’s less likely to cause drowsiness than some other muscle relaxers (for example, cyclobenzaprine).
The bottom line
Methocarbamol is a medication that treats muscle-related pain. Though we don’t know exactly how it works, methocarbamol’s mechanism of action is likely related to its effects on the brain. It may also have a direct effect on your muscles. It's believed to work within the brain to relax your muscles. And it may also directly block sodium channels in muscle, causing them to stay relaxed longer.
Muscle relaxers like methocarbamol aren’t the first-choice treatment option for muscle pain. Non-medication treatments like physical therapy, rest, and heat application are usually recommended first. Then, nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin), naproxen (Aleve), or meloxicam (Mobic) are often recommended. Muscle relaxers like methocarbamol may be an option at this point as well.
Methocarbamol is less likely to cause drowsiness than some other muscle relaxers.
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References
2023 American Geriatrics Society Beers Criteria Update Expert Panel. (2023). American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society.
Dave, H. D., et al. (2023). Anatomy, skeletal muscle. StatPearls.
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Qaseem, A., et al. (2017). Noninvasive treatments for acute, subacute, and chronic low back pain: A clinical practice guideline from the American College of Physicians. Annals of Internal Medicine.
Qaseem, A., et al. (2020). Nonpharmacologic and pharmacologic management of acute pain from non–low back, musculoskeletal injuries in adults: A clinical guideline from the American College of Physicians and American Academy of Family Physicians. Annals of Internal Medicine
See, S., et al. (2008). Choosing a skeletal muscle relaxant. American Family Physician.
Selected Health Conditions and Likelihood of Improvement with Treatment. (2020). 5 musculoskeletal disorders. National Academies Press.
Sibrack, J., et al. (2022). Methocarbamol. StatPearls.
Spence, M. M., et al. (2013). Risk of injury associated with skeletal muscle relaxant use in older adults. The Annals of Pharmacotherapy.
Trueman, C., et al. (2020). Inappropriate use of skeletal muscle relaxants in geriatric patients. U.S. Pharmacist.
Zhang, Y., et al. (2020). Methocarbamol blocks muscular Nav1.4 channels and decreases isometric force of mouse muscles. Muscle & Nerve.
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