Skeletal Muscle Relaxants; Uses, Indications, Side Effects

Skeletal muscle relaxants include a variety of structurally unrelated compounds that can be classified into two main categories: antispasticity and antispasmodic medications. These agents have different indications, mechanisms of action, and side-effect profiles. Understanding these differences can improve selection of an appropriate agent to optimize patient-specific therapy.

Muscle relaxants treat two main conditions spasticity (stiff, rigid muscles) caused by conditions such as cerebral palsy, multiple sclerosis, and stroke; or muscle spasms which are typically temporary and associated with conditions such as a tension headache, low back pain, or fibromyalgia.

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.

Only three muscle relaxants – baclofen, dantrolene, and tizanidine are FDA approved to treat general spasticity; however, six (carisoprodol, chlorzoxazone, cyclobenzaprine, metaxalone, methocarbamol, and orphenadrine) are approved to treat muscle spasm. Botulinum toxin is only approved to treat spasticity in certain muscle groups of the upper and lower limbs. Many other medications are also used to treat spasticity or muscle spasm although most are not approved for this indication.

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.

For a full list of people who should not take each type of muscle relaxant, refer to the specific leaflet for that medication.

  • Baclofen should not usually be given to people who have a stomach ulcer, epilepsy, mental health problems or diabetes.
  • Dantrolene should not be given to people with liver, heart or breathing problems.
  • Diazepam should be avoided in people who have severe breathing difficulties – for example, people who have myasthenia gravis and people with lung problems.
  • Tizanidine should not usually be given to elderly people, or people who have severe problems with their liver.
  • Methocarbamol should not be used for people who have myasthenia gravis or severe breathing problems. It also should not be used in people with epilepsy or brain damage.
  • Cannabis extract can only be prescribed by specialists for people with multiple sclerosis. People who have a personal or family history of hallucinations or delusions or any other severe psychiatric disorder should not take cannabis extract.

There are several types of muscle relaxant medications commonly used to treat back pain or neck pain.

Common Muscle Relaxant Medications

Skeletal Muscle Relaxants

Medication Indication Common Dosage Metabolism Dose Adjustments
Antispasticity Agents
  • Baclofen (Lioresal)
Spasticity 5 mg 3 times daily
Max: 80 mg daily
Hepatic (15%) None
  • Dantrolene (Dantrium)
Spasticity, malignant hyperthermia Initial: 25 mg daily
Maintenance: 25–100 mg up to 4 times daily
Hepatic (extensive) None
Antispasmodic Agents
  • Carisoprodol (Soma)
Acute musculoskeletal pain 250–350 mg 3 times a day and at bedtime
Max: 1,400 mg daily
Hepatic (2C19) Active metabolite: meprobamate Liver disease: Use lower initial dose and increase gradually as needed/tolerated
  • Chlorzoxazone (Parafon Forte DSC)
Acute musculoskeletal pain 500 mg 3–4 times daily
Max: 750 mg 3–4 times daily
Hepatic (glucuronidation) None
  • Cyclobenzaprine (Amrix)
Acute musculoskeletal pain IR: 5 mg 3 times daily
Max: 10 mg 3 times daily
ER: 15 mg daily
Max: 30 mg daily
Hepatic (CYP3A4, 1A2) Renal, none; hepatic, use with caution
  • Metaxalone (Skelaxin)
Acute musculoskeletal pain 800 mg 3–4 times daily Hepatic (CYP1A2, 2D6, 2E1, 3A4) Contraindicated in severe hepatic and renal dysfunction
  • Methocarbamol (Robaxin)
Acute musculoskeletal pain Initial: 1,500 mg 4 times daily for 2–3 days
Maintenance: 750 mg every 4 hours, 1,500 mg by mouth 3 times daily, or 1,000 mg 4 times daily
Max: 4 g daily
Conjugation, dealkylation, and hydroxylation None
  • Orphenadrine (Norflex)
Acute musculoskeletal pain 100 mg 2 times daily Hepatic (extensive) None
Antispasticity and Antispasmodic Agents
  • Diazepam (Valium)
Relief of skeletal muscle spasm 2–10 mg 3 to 4 times daily Hepatic (2C19, 3A4) Renal, none; hepatic, decrease by 50%
  • Tizanidine (Zanaflex)
Spasticity Initial: 4 mg up to 3 times daily; may titrate to optimal effect in 2–4 mg increments as needed to a max of 3 doses in 24 hours Hepatic (1A2) Renal, use with caution if CrCl < 25 mL/min; hepatic, avoid use in severe impairment
Medication Beers Criteria Special Precautions Adverse Effects Clinical Pearls
Antispasticity Agents
  • Baclofen (Lioresal)
No Geriatric: 5 mg 2–3 times daily; use lowest effective dose CNS depression Boxed warning: Avoid abrupt discontinuation due to risk of withdrawal
  • Dantrolene (Dantrium)
No May cause sun sensitivity Major hepatic impairment including fatal hepatitis, CNS depression, difficulty swallowing Boxed warning: risk for hepatotoxicity with chronic use; routine use not recommended
Antispasmodic Agents
  • Carisoprodol (Soma)
Yes Has been subject to abuse, dependence, withdrawal, misuse, and criminal diversion Drowsiness, dizziness, headaches, somnolence, seizure Schedule IV
Active metabolite with barbiturate effects; some evidence suggests sedation is primary mechanism of action without direct effects on skeletal muscle. Limit use to 2–3 weeks.
  • Chlorzoxazone (Parafon Forte DSC)
Yes Idiosyncratic and unpredictable hepatotoxicity (rare but serious) CNS depression Periodic LFTs recommended during chronic use
  • Cyclobenzaprine (Amrix)
Yes Caution with elderly and hepatic impairment Anticholinergic effects, CNS depression, rare arrhythmias Structure similar to tricylic antidepressants. Do not use longer than 2–3 weeks; do not use within 14 days of monoamine oxidase inhibitors.
  • Metaxalone (Skelaxin)
Yes Monitor liver function in mild-to-moderate hepatic dysfunction CNS depression, nausea, vomiting; rare: jaundice, hemolytic anemia, elevated LFTs Mechanism associated with sedative properties; take with food
  • Methocarbamol (Robaxin)
Yes Geriatrics, liver, and renal impairment: Use lower initial doses and increase gradually as needed/tolerated Dizziness, headache, lightheadedness Mechanism associated with CNS depression; drug may change color of urine to brown, black, or green
  • Orphenadrine (Norflex)
Yes Caution in patients with heart failure (palpitations, tachycardia); do not crush Anticholinergic effects Euphorigenic and analgesic properties; must taper in chronic use
Antispasticity and Antispasmodic Agents
  • Diazepam (Valium)
Yes Elderly: 2–2.5 mg 1–2 times daily; titrate gradually as tolerated Drowsiness, fatigue, and ataxia Schedule IV
Avoid abrupt discontinuation after extended therapy
  • Tizanidine (Zanaflex)
No Elderly: use with caution due to decreased clearance Somnolence, xerostomia, and weakness Concomitant use with other psychotropics may cause additive sedation; monitor liver function; avoid rapid discontinuation

CNS = central nervous system; CrCl = creatinine clearance rate; ER = extended release; IR = immediate release; LFT = liver function test; Max = maximum

Muscle relaxants usually used to treat back pain and other types of pain include:

  • Baclofen – 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 – 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.
  • Diazepam (e.g. Valium)  – In 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   – 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.

But others muscle relaxant that all are not approved by FDA

  • Amrix
  • arbaclofen
  • baclofen
  • carisoprodol
  • chlorzoxazone
  • cyclobenzaprine
  • Dantrium
  • dantrolene
  • Diastat
  • Diastat AcuDial
  • diazepam
  • Fexmid
  • Flexeril
  • Gablofen
  • Lioresal
  • Lorzone
  • metaxalone
  • methocarbamol
  • Norflex
  • Ontinua ER
  • orphenadrine
  • Parafon Forte DSC
  • Revonto
  • Robaxin
  • Ryanodex
  • Skelaxin
  • Soma
  • Valium

Home Remedies of Muscle Relaxant

Apple Cider Vinegar

Apple cider vinegar has anti-inflammatory and alkalizing properties that help reduce inflammation. Folks use it for treating their leg cramps and aching muscles, since it is high in potassium and loaded with several nutrients.  Combine 2 tsp of apple cider vinegar, 1 tsp of honey, a twig of fresh mint and 8 -10 ounces of chilled water. Mix them well and consume.

  • Alternatively, you can simply add 2 tbsp of apple cider vinegar in a glass of warm water and drink it.
  • Moreover, you can also rub the vinegar directly on the affected area.
  • Besides, add 2 cups of apple cider vinegar to the lukewarm water in a bath tub. Soak in it for 20 minutes. Do this daily until you recover completely.

Clove Oil

  • Clove oil contains anti-inflammatory properties that reduce muscular cramp and alleviate pain effectually. Massage lukewarm clove oil on the affected area for at least 5 minutes.

Epsom Salt

  • Epsom salt contains magnesium that heals soreness of muscles and provides relaxation. Fill the tub with warm water. Then add 2 cups of epsom salt and mix it thoroughly. Soak the affected area it for 20 minutes. Taking this bath once daily will surely resolve your problem.

Cold Compress

  • The cold temperature can numb the pain since it reduces soreness and relaxes the affected muscles. Wrap some ice cubes in a thin towel and put them on the affected area for around 15 minutes. Repeat this process every two hours for a few days. Moreover, you can also go for a cold shower, in order to relax your sore muscles.


  • In order to ease the stiffness and soreness of muscles, massage on the affected muscles. Relax your muscles by using long strokes and wrap the area with a warm towel. Besides, you can also prepare massage oil by mixing four parts of vegetable oil in one part of wintergreen oil. Wintergreen oil contains methyl salicylate which stimulates blood flow and relieves pain.

Stretching Exercises

  • Stretch the affected muscle for 15 to 30 seconds at a time. Performing simple stretching workout can relieve the muscle cramps. Alternatively, go for swimming as muscles stretch in water easily, which reduces inflammation and soreness.

Tart Cherry

  • Anti-inflammatory and antioxidant compounds in tart cherries reduce the inflammation and put off the post-exercise muscle pain. Drink a cup of tart cherry juice (without sweetening) to reduce muscle soreness and tenderness. Alternatively, eat 1½ cups of tart cherries post workout.


  • The deficiency of potassium causes fatigue, muscle weakness and cramps. Being a good source of potassium, banana reduces muscle pain. Eat one or two ripe bananas on daily basis to treat achy muscles. Besides, drink a glass full of banana milkshake. It contains both potassium and calcium that plays an important role in maintaining healthy muscles.


  • Milk is an excellent source of calcium. It is essential to include an adequate amount of calcium in your daily diet. One should drink at least 2-3 glasses of milk every day.


  • A cup of coffee may help reduce muscle soreness in women after a strenuous workout. It works by blocking adenosine, a chemical released by your body in response to injury. Don’t overdo this, as too much caffeine can cause muscle spasms.

 Coconut Oil

  • Coconut oil is highly recommended for treating several ailments. Use 2-3 tbsp of virgin coconut oil every day in cooking to avail its benefits.

Take a Break

  • Sometimes the best remedy to alleviate muscle pain is not to do anything at all.  If you take a break from your daily schedule and rest for a couple of days, then common muscle pain will pass on naturally.

Mustard Oil

  • Mustard oil is a natural rubefacient that increases the blood flow, loosens up the muscles and helps alleviate pain. Crush 10 garlic cloves and heat them in 4 tbsp of mustard oil till the cloves turn golden brown. Now, put a little piece of camphor in it. Leave the mixture to cool and strain afterward. Gently massage the oil on the painful area. Do this multiple times a day, for a few weeks.


  • Turmeric is a potent painkiller and works as an anti-inflammatory agent. Take freshly grated turmeric, lemon juice and salt in equal proportion to make a poultice. Apply it onto the sore muscles and leave it for 30 minutes. Afterward wash off with warm water. Do this twice daily. Alternatively, add one teaspoon of turmeric powder in a glass of warm milk. Drink it twice a day for quick internal recovery.

Black Tea

  • Brew a cup of black tea to relax your muscles after a tough workout. Theaflavin, an antioxidant found in black tea, helps reduce inflammation and also eliminates free radicals from the muscle cells. Simply boil a half cup of water.  Add 1 tsp tea leaves and simmer it on the low flame. Stir the solution well and strain after 2 minutes. Add sugar to taste.


  • Ginger improves circulation of blood flow, thereby relieves muscle pain. Cut a small piece of ginger root and allow it to boil in two cups of water for 8-10 minutes. Strain the infusion. Add honey to sweeten the taste. Alternatively, wrap 4 tbsp of freshly crushed ginger in a tight piece of cotton cloth or bag. Put this in hot water for ½ minute and allow it to cool. Now, put it on the painful area for 15 minutes. Repeat it several times a day for 3 days.

Cayenne Pepper

  • Cayenne pepper is loaded with analgesic and anti-inflammatory properties that reduce inflammation, muscle pain and stiffness. Take 5 tsp of cayenne pepper and add it to ½ cup of coconut oil. Slightly warm this mixture and leave it for 24 hours. Afterward, strain the oil and keep it in an airtight container. Gently massage the affected area with this oil 2-3 times a day, for a few days. Or else, take one tablespoon of olive oil and mix one teaspoon of cayenne pepper powder in it. Apply it on the affected area. Now, cover it with a bandage and leave it overnight. Follow this remedy for 2-3 days.

Moreover, sprinkle some crushed cayenne pepper flakes in your soup, salad, or other dishes to speed up the recovery.

  • Vegetable Soup – Soup is also among the best foods that relax your nerves. This works well because it helps to get rid of foreign bodies and infections from your body which are one of the main reasons that get many people uneasy. You should go with soups that contain vegetables like tomatoes, green peppers, carrots and you can also add garlic, spinach, thyme and many other ingredients that you could use to improve your well being.
  • Milk – If you need a quick calming effect, reach out for a glass of warm milk. Warm milk is known to contain tryptophan –a compound which helps in the production of serotonin (around 43%). Serotonin is known to induce a feeling of pleasure along with helping in sleep. You can always take in cold milk during the day to avoid drowsiness for cold milk is still rich in calcium which also induces calmness.
  • Celery – Historically, celery was regarded as an antidote for stress, with Hippocrates prescribing the vegetable as a tonic for those suffering from nervous tension. Today, nutritionists recognize the daily ingestion of celery as an effective plan to lower high blood pressure. Lower blood pressure leads to a better ability to relax.
  • Oatmeal – As long as it is sugar-free, oatmeal aids in relaxation for several reasons. First, this complex carbohydrate enhances the absorption of tryptophan, which leads to the production of serotonin – a brain chemical that helps the body relax. In addition, oats are rich in Vitamin B6 – a known anti-stress vitamin and melatonin, a hormone that supports a healthful relaxation and sleep
  • Cold Water Fish – Cold water fish such as mackerel, tuna, salmon, sardines and herring are high in omega-3 fatty acids. Omega-3s help boost serotonin levels while suppressing the production of anxiety-related hormones cortisol and adrenaline. In addition, omega-3s have been shown to lower high blood pressure.
  • Bananas – This fruit is loaded with potassium and magnesium, known natural muscle relaxants. Because relaxed muscles encourage the body to relax, sources of potassium and magnesium (like bananas) are a wise route towards easing physically mounted stress.  Bananas also contain tryptophan, which promotes serotonin release in the brain.
  • Dark Chocolate – Dark chocolate helps to reduce stress levels in the brain and this can be done because it contains serotonin, endorphin and dopamine, which are great hormones for the mollifying of stress level in the brain.  Be sure to eat 70% of more cacao.
  • Nuts and seeds – Nuts are rich in magnesium,selenium, zinc, vitamin E and vitamin B-complex that help relax the brain when taken in large quantities. Peanuts and pumpkin seeds are rich in magnesium but peanuts also have high sodium content which is why they are not good for your health when taken in large amount.
  • Eggs – Just like milk, eggs are a source of amino acids packed with tryptophan which is a relaxing brain chemical. Make sure you include eggs in your diet either in breakfast or as a snack.


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Skeletal muscle relaxants

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