Updated on November 22, 2023
7 min read

How Muscle Relaxers Affect the Body & Their Potential Risks

Key Takeaways

  • Muscle relaxers are medications that alleviate muscle stiffness, spasms, and pain
  • Muscle relaxers can cause dependency and other serious side effects
  • Muscle relaxers can interact with alcohol and other CNS depressants, leading to adverse effects
  • You can become addicted to muscle relaxants with long-term use
  • If you or someone you know suffers from a muscle relaxant addiction, contact a healthcare professional for help

How Do Muscle Relaxers Work?

Muscle relaxants alleviate pain, muscle tightness, and other symptoms from muscle spasms and rigidness. They work at many levels, primarily affecting the brain and skeletal muscles.

There are two categories of muscle relaxants:

  • Antispasmodics: They relieve, prevent, and decrease muscle spasms affecting smooth muscles. These drugs also aid organs in alleviating spasms in the gastrointestinal area.
  • Antispastics: They treat and relieve spasticity in skeletal muscles, especially in conditions like multiple sclerosis and cerebral palsy. 

Muscle tightness happens because of increased nerve signals. Muscle relaxants work by reducing these signals, causing a calming effect.


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What are Muscle Relaxers?

Muscle relaxants treat certain disorders that produce muscle spasms or stiffness. They can also treat acute and, in some cases, chronic pain.

Acute pain is sudden and lasts for a short time. Chronic pain can last up to 6 months or longer. Other uses for muscle relaxants include treating restless leg syndrome and sore muscles.

What are Muscle Spasms?

Muscle spasms or cramps are quick, unexpected muscle contractions. On the other hand, muscle spasticity is a continuous spasm that causes muscle stiffness or tightness.

The most common type of cramp is a skeletal muscle spasm. These spasms are usually abrupt, painful, and short-lived.

Physicians use muscle relaxers or relaxants to treat spasms due to cramps and muscle tightness. They reduce muscle tone, which refers to muscles' inherent tension or resistance to passive stretching while in a state of relaxation.

Neck and Back Pain Treatment

Doctors commonly prescribe muscle relaxers for back pain, especially for neck pain and upper or lower back pain.

While they aren't more effective than non-steroidal anti-inflammatory drugs (NSAIDs) for pain, physicians recommend them because they help with relaxation and sleep. Always use them alongside rest and physical therapy.

Treatment for Other Disorders

Muscle relaxants may also treat other conditions, including:

  • Cerebral palsy
  • Multiple sclerosis (MS)
  • Motor neuron disease (MND)
  • Head or spinal cord injuries
  • Irritable bowel syndrome (IBS)

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What are the Treatment Types for Muscle Spasms and Spasticity?

Many classes of medications help with muscle spasms and spasticity. They can include NSAIDs, prescription muscle relaxants, and alternative medicine.

The following is an overview of the most common drugs that relieve muscle spasms:

Over-the-counter (OTC) Treatments

Doctors typically prescribe OTC medications first. The following drugs are NSAIDs:

Generic nameBrand nameFormUsed to treat
AcetaminophenTylenol, ParacetamolTablet, Capsule, Liquid, Injection, SuppositoryMinor aches and pains, Fever
IbuprofenAdvil, MotrinTablet, Capsule, Liquid, InjectionPain, Inflammation, Fever 
NaproxenAleveTablet, Liquid, SuppositoryAcute pain, Inflammation

Prescription Muscle Relaxants

Doctors prescribe prescription muscle relaxants for severe pain, along with rest and physical therapy. They’re beneficial when you can’t tolerate OTC medications due to certain side effects.

Antispasmodic prescription muscle relaxants, or centrally acting SMRs, include:

Generic nameBrand nameFormUsed to treat
CarisoprodolSomaTabletSkeletal muscle pain or injury
ChlorzoxazoneParafon Forte, LorzoneTabletMuscle spasms, muscle pain, musculoskeletal conditions
CyclobenzaprineFexmid, Flexeril, AmrixTablet, Extended-release capsuleSkeletal muscle pain or injury
MetaxaloneSkelaxin, MetaxallTabletSkeletal muscle pain or injury
MethocarbamolRobaxinTabletSkeletal muscle pain or injury
OrphenadrineNorflexExtended-release tabletSkeletal muscle pain or injury, Parkinson’s Disease
TizanidineZanaflexTablet, CapsuleMultiple Sclerosis, Spinal cord injury

Antispastic Prescription Muscle Relaxers

Some types of antispastic prescription muscle relaxers include:

Generic nameBrand nameFormUsed to treat
BaclofenLioresal, GablofenTablet, InjectionMultiple Sclerosis
DantroleneDantriumTabletMultiple Sclerosis, Cerebral Palsy, Strokes, Spinal cord injury
DiazepamValiumOral suspension, Tablet, InjectionInflammation, Muscle trauma, Muscle spasticity

Off-Label Medications for Spasticity

Doctors can prescribe certain medications for certain conditions, even when the U.S. Food and Drug Administration (FDA) hasn’t approved the drugs for that purpose. This is called off-label drug use.

Some off-label medications aren’t technically muscle relaxants. However, physicians may prescribe them to relieve symptoms of spasticity. These drugs include:

Generic nameBrand nameFormUsed to treat
ClonazepamKlonopinTabletSeizures, Anxiety, Muscle spasms
LorazepamAtivanTablet, LiquidAnxiety, IBS, Substance withdrawal
AlprazolamXanaxTablet, LiquidAnxiety, Panic attacks, Muscle spasms
ClonidineKapvay, Catapres, JenlogaTabletHigh blood pressure, ADHD, Muscle Spasms, Spasticity
GabapentinNeurontin, Gralise, HorizantTablet, LiquidSeizures, Nerve pain, Restless leg syndrome

All-Natural Muscle Relaxers

There’s little to no scientific evidence to support the effectiveness of these all-natural muscle relaxers. Although the FDA doesn’t approve the medicinal use of these substances, many people believe they are effective for pain relief.

Some popular all-natural muscle relaxers include:

Generic nameFormUsed to treat
Cannabidiol (CBD)Tinctures and oil, Topical, CapsulePain, Dystonia, Insomnia
Cherries and blueberriesFruit, JuiceMuscle pain, Inflammation
Cayenne pepperFood, Capsule, TopicalFibromyalgia Rheumatoid arthritis
ChamomileTea, OilMuscle spasms, Sore muscles
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What are the Common Side Effects of Muscle Relaxers?

The most common muscle relaxant side effects include:

  • Tiredness and drowsiness
  • Weakness
  • Dizziness
  • Nausea
  • Agitation
  • Light-headedness
  • Headaches
  • Forgetfulness
  • Muscle weakness (side effect of Diazepam)
  • Confusion
  • Shakiness
  • Sweating
  • Anxiety
  • Blurred Vision
  • Appetite Changes
  • Decreased blood pressure
  • Constipation
  • Dry mouth

Avoid activities that require mental alertness or coordination when taking these drugs. These include driving and using heavy machinery, which can lead to accidents and injuries while under muscle relaxers.

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Are Muscle Relaxers Addictive?

Muscle relaxants can be habit-forming, and they aren't FDA-approved for long-term use. Safe usage is typically limited to short-term treatments of 2 to 3 weeks.

Extended use can lead to tolerance and dependency. It also causes central nervous system depression, leading to sedation and impaired coordination. 

Such effects increase the risk of falls or accidents. Common muscle relaxants, such as Soma and Flexeril, can cause tolerance and dependence when used for extended periods.

Signs You’re Addicted to Muscle Relaxers

These warning signs can help identify whether someone might be abusing muscle relaxers:

  • Taking a muscle relaxer when a prescription no longer indicates it
  • Requiring more of the drug to feel the same effects
  • Faking symptoms to receive more prescription refills
  • Changes in physical appearance, hygiene, and behavior suddenly
  • Combining a muscle relaxer with other substances to experience a more intense high
  • Overdosing

Muscle Relaxant Withdrawal Symptoms

If you suddenly stop using muscle relaxers after long-term use, it can result in withdrawal symptoms, including:

  • Nausea
  • Headache
  • Drowsiness
  • Malaise
  • Discomfort
  • Seizures
  • Hallucinations

These symptoms usually peak between 2 to 4 days after the last dose. However, they can last for up to 2 weeks.

Overdose Symptoms of Muscle Relaxant Use

Users abuse muscle relaxants for their euphoric and dissociative effects. In 2021, 16,706 Americans lost their lives due to prescription opioid overdoses.1

Muscle relaxant overdose symptoms include:

  • Stupor
  • Hallucinations
  • Shock
  • Seizures
  • Hyperventilation
  • Cardiac arrest
  • Coma
  • Death

How Do You Treat Muscle Relaxant Addiction?

The most common treatment methods for muscle relaxant addiction include:

If you or someone you know suffers from a muscle relaxant addiction, contact a healthcare professional to review your treatment options.

What Causes Muscle Spasticity?

Muscle spasms often originate from damage to an area of the brain or spinal cord that regulates voluntary movement. Conditions that lead to muscle spasticity include:

  • Cerebral Palsy (CP)
  • Multiple sclerosis (MS)
  • Spinal cord injuries
  • Traumatic brain injuries
  • Brain damage
  • Stroke
  • Encephalitis
  • Meningitis
  • Adrenoleukodystrophy (ALD)
  • Amyotrophic lateral sclerosis (Lou Gehrig's disease or ALS)
  • Phenylketonuria

Non-Medical Factors

  • Not stretching enough, including before exercise
  • Muscle overuse
  • Muscle fatigue
  • Exercising in the heat
  • Dehydration
  • Electrolyte depletion, including potassium, magnesium, and calcium
  • Involuntary nerve discharges
  • Decrease in blood supply
  • Stress

Conditions Associated with Muscle Spasms

Muscle spasms on their own are symptoms of another underlying condition, including:

  • Back pain
  • Neck pain
  • Fibromyalgia
  • Obesity
  • Diabetes
  • Anemia (low red blood cell count)
  • Kidney disease
  • Hormone issues (thyroid disorders)

Side Effects and Signs of Muscle Spasticity

Muscle spasticity adversely affects the joints and extremities, especially in growing children. It can also interfere with everyday activities such as walking, talking, or bending.

Symptoms range from mild limitations to movement to the inability to move affected areas. Another sign includes severe pain during movement.

What are Muscle Relaxant Drug Interactions?

Don’t use muscle relaxants with the following:

These interactions can lead to severe side effects, including respiratory depression. Inform your healthcare provider about all your medications before taking muscle relaxants.

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Updated on November 22, 2023
12 sources cited
Updated on November 22, 2023
  1. Drug Overdose Death Rates.” National Institute on Drug Abuse, 2023.
  2. Li et al. “Utilization Patterns of Skeletal Muscle Relaxants Among Commercially Insured Adults in the United States from 2006 to 2018.” Pain Medicine, 2021.
  3. Witenko et al. “Considerations For The Appropriate Use Of Skeletal Muscle Relaxants For The Management Of Acute Low Back Pain.” Pharmacy and Therapeutics, 2014.
  4. Patel et al. “Efficacy and Safety of Combination of NSAIDs and Muscle Relaxants in the Management of Acute Low Back Pain.” Pain and Therapy, 2019.
  5. Richards et al. “Muscle relaxants for pain management in rheumatoid arthritis.” Research Gate, 2012.
  6. Austin, D. “Everything to know about muscle relaxers: When to take them and whether they're dangerous.” USA Today, 2023.
  7. CARISOPRODOL (Trade Name Soma).” United States Department of Justice, 2019.
  8. FLEXERIL® (CYCLOBENZAPRINE HCL) TABLETS.” United States Food and Drug Administration, 2013.
  9. See et al. “Skeletal Muscle Relaxants.” United States National Library of Medicine, 2008.
  10. See et al. “Choosing a Skeletal Muscle Relaxant.” American Family Physician, 2008.
  11. Soprano et al. “Assessment of Physician Prescribing of Muscle Relaxants in the United States, 2005-2016.” JAMA Network, 2020.
  12. UF Study Finds Some Combinations of Opioids and Muscle Relaxants Are Safe, Others Raise Overdose Risk." University of Florida College of Pharmacy, 2020.

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