Muscle Relaxants: List of Common Muscle Relaxers

Muscle relaxers are prescription medications that help regulate muscle contraction (tightening) to reduce pain and discomfort caused by muscle spasms and muscle spasticity (stiffness).

Short-term use of muscle relaxers relieves pain caused by tense or spasming muscles and improves daily functioning.¹Barreto TW, Lin KW. Noninvasive Treatments for Low Back Pain. American Family Physician. 2017;96(5):324-327. Accessed August 14, 2023. https://www.aafp.org/pubs/afp/issues/2017/0901/p324.html

Muscle relaxers are the third most prescribed medication for low back pain.²Cashin 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. Published 2021 Jul 7. doi:10.1136/bmj.n1446

When Muscle Relaxers are Prescribed

Muscle relaxers are prescribed when there is severe pain, discomfort, and/or functional disability due to muscle spasms or stiffness.¹Barreto TW, Lin KW. Noninvasive Treatments for Low Back Pain. American Family Physician. 2017;96(5):324-327. Accessed August 14, 2023. https://www.aafp.org/pubs/afp/issues/2017/0901/p324.html  The decision to prescribe a muscle relaxer is based on the following factors: 

• When over-the-counter (OTC) and non-drug therapies (eg, physical therapy, stretching, or heat therapy) are ineffective¹Barreto TW, Lin KW. Noninvasive Treatments for Low Back Pain. American Family Physician. 2017;96(5):324-327. Accessed August 14, 2023. https://www.aafp.org/pubs/afp/issues/2017/0901/p324.html
• To prevent muscle spasms/stiffness and potential injury following spine surgery or during a physical therapy session¹Barreto TW, Lin KW. Noninvasive Treatments for Low Back Pain. American Family Physician. 2017;96(5):324-327. Accessed August 14, 2023. https://www.aafp.org/pubs/afp/issues/2017/0901/p324.html
• In addition to OTC pain medication, rest, physical therapy, and other non-drug therapies to relieve discomfort and improve function³Conermann T, Christian D. Carisoprodol. [Updated 2022 Nov 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK553077/

The duration of treatment is generally short (2-3 weeks).⁴Li Y, Delcher C, Reisfield GM, Wei YJ, Brown JD, Winterstein AG. Utilization Patterns of Skeletal Muscle Relaxants Among Commercially Insured Adults in the United States from 2006 to 2018. Pain Med. 2021;22(10):2153-2161. doi:10.1093/pm/pnab088

Factors that Affect the Type of Muscle Relaxer Prescribed

Choosing a muscle relaxer depends on the cause of the pain (muscle spasms or stiffness, or both). 

Potential side effects and medication interactions, concomitant medical conditions, and personal preferences are also considered.

Types of Prescription Muscle Relaxers

Muscle relaxers are categorized based on their ability to treat stiffness, spasms, or both.

• Antispastic drugs. These medications reduce tightness in the muscle through various mechanisms in the brain and directly within the muscle tissue.⁵Rivelis Y, Zafar N, Morice K. Spasticity. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507869/
• Antispasmodic drugs. These medications stop the spontaneous or involuntary contraction of muscles (such as jerks, twitches, or cramps) that cause spasms.³Conermann T, Christian D. Carisoprodol. [Updated 2022 Nov 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK553077/

Two medications, tizanidine and diazepam, have both antispastic and antispasmodic activity.⁵Rivelis Y, Zafar N, Morice K. Spasticity. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507869/

How Muscle Relaxers May Be Given

Muscle relaxers are given orally (by mouth) or via an injection, and in rare cases, the drug is delivered directly into the spinal cord through an implanted device.⁶Kim J, De Jesus O. Medication Routes of Administration. [Updated 2023 Feb 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK568677/

An oral muscle relaxer is more commonly prescribed because it is convenient to take and does not require needles.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Underlying medical conditions and the severity and expected duration of pain and/or disability may be reasons to consider an injectable form.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Oral administration of muscle relaxers

Oral muscle relaxers are taken by mouth in the form of a tablet or capsule. As the drug moves through the gastrointestinal tract, it is slowly absorbed into the bloodstream and delivered to the brain and other areas of the body.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Intramuscular (IM) administration of muscle relaxers

IM injection involves delivering medication into a large muscle with a lot of blood vessels, such as the thigh or buttock muscle. The medication is slowly absorbed into the bloodstream and then delivered throughout the body.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

IM muscle relaxers are typically used in emergency or urgent care settings when a quick onset of action is preferred. They are also used when a person has difficulty swallowing.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Intravenous (IV) administration of muscle relaxers

IV injection delivers the drug through a vein and directly into the bloodstream. This method allows the medication to travel quickly to the brain and other areas of the body and provides quick relief.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Intravenous muscle relaxers are reserved for use in a hospital or other clinical setting.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Intrathecal (IT) administration of muscle relaxers

The intrathecal route involves delivering medication directly into the fluid surrounding the spinal cord, typically through an implanted pain pump.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/  The intrathecal route uses a smaller dose of medication, causing fewer or less intense side effects.⁷Ghanavatian S, Derian A. Baclofen. [Updated 2022 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526037/

Intrathecal muscle relaxers are generally only used in cases of severe spasticity from an underlying chronic condition such as cerebral palsy.⁸Drugs@FDA: FDA-Approved Drugs. www.accessdata.fda.gov

Common Muscle Relaxers and Their Effects

The following table lists the commonly prescribed muscle relaxers, the types of muscle issues they treat, and the mode of delivery.

Antispasmodic muscle relaxers are more frequently prescribed for back and neck pain compared to antispastics.²Cashin 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. Published 2021 Jul 7. doi:10.1136/bmj.n1446

When Muscle Relaxers May Be Prescribed for Back and Neck Pain

Muscle relaxers are prescribed when muscle spasms or spasticity are suspected as the cause of the pain, such as in cases of ¹Barreto TW, Lin KW. Noninvasive Treatments for Low Back Pain. American Family Physician. 2017;96(5):324-327. Accessed August 14, 2023. https://www.aafp.org/pubs/afp/issues/2017/0901/p324.html :

• Injury or trauma
• Muscle strain
• Poor posture
• Spinal conditions (eg, scoliosis)
• Neurological conditions (eg, multiple sclerosis and cerebral palsy) 
• Nerve inflammation or compression (sciatica)

The effectiveness of muscle relaxers differs for each person.¹⁹Qaseem A, Wilt TJ, McLean RM, et al. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. Ann Intern Med. 2017;166(7):514-530. doi:10.7326/M16-2367 Factors such as the underlying cause of pain and the use of other OTC or non-drug therapies play a role in the overall effectiveness of the treatment.²Cashin 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. Published 2021 Jul 7. doi:10.1136/bmj.n1446

See 6 Things to Know About Muscle Relaxants

Safety Profile of Muscle Relaxers

Muscle relaxers are generally safe and well-tolerated when used short-term at recommended doses.²Cashin 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. Published 2021 Jul 7. doi:10.1136/bmj.n1446

Sedation and drowsiness are the most commonly reported side effects, but factors such as underlying conditions and the use of other medications may increase the risk.⁹Baclofen. Package Insert. Advagen Pharma Limited; 2023^-18Orphenadrine. Package Insert. Amneal Pharmaceuticals of New York LLC; 2019

It is advisable to discuss the potential side effects and risks with a doctor.