Methocarbamol (Robaxin) Tablets/ Injection - Uses, Dosage, Side effects

A centrally acting muscle relaxant is methocarbamol (Robaxin). In addition to physical therapy and painkillers, it is used to treat severe painful spasms. It is available as 500 mg and 750 mg oral tablets and as injections for intravenous and intramuscular use.

Methocarbamol (Robaxin) Uses:

  • It is used to alleviate muscular spasms that are a side effect of acutely painful musculoskeletal diseases.
  • It is especially helpful in patients with back pain and muscle spasms of recent onset. It is least helpful in those patients who have a chronic condition such as patients with contractures and cerebral palsy.
  • It is also least likely to benefit acute inflammatory conditions such as gout and arthritis as these conditions are caused by joint inflammation rather than muscle spasms.

Methocarbamol (Robaxin) Dose in adults:

Methocarbamol (Robaxin) Dose in the treatment of Muscle spasm:

  • Oral tablets:
    • 1.5 g orally four times a day for 2-3 days (In severe conditions, up to 8 g/day may be given).
    • The dose is then reduced to 4-4.5 g/day in 3-6 divided doses
  • Intramuscular, Intravenous formulation:
    • 1 gm initially.
    • The dose may be repeated every eight hours if oral treatment is not possible.
    • The maximum dose is 3 g/day not exceeding three consecutive days.
    • After a 48-hour period without using any drugs, the treatment may be repeated if the situation doesn't improve.

Methocarbamol (Robaxin) Dose in the treatment of Tetanus:

  • Initial dose: 1-2 g intravenously by direct IV injection.
  • This is followed by an additional 1-2 gms by an intravenous infusion.
  • The maximum initial dose is 3 gms in total.
  • Up until the nasogastric tube or oral treatment is feasible, the initial dose may be administered once every six hours.
  • Up to 24 gms of the total dose may be required.
  • A maximum of three consecutive days should pass before administering the injection.

Methocarbamol (Robaxin) Dose in Childrens:

Methocarbamol (Robaxin) Dose in the treatment of Muscle spasm:

  • Adolescents older than 16 years:

    • 1,500 mg orally four times a day for 2 - 3 days.
    • The maximum daily dose is 8 gms/day (reserved higher doses for severe conditions).
    • The dose should be reduced to 4,000 to 4,500 mg/day in 3 - 6 divided doses (ie, 1,000 mg four times a day or 750 mg every four hours or 1,500 mg three times a day)

Methocarbamol (Robaxin) Dose in the treatment of Tetanus:


  • Use alternative medicines such as benzodiazepines.
  • Infants, Children, and Adolescents:

    • 15 mg/kg/dose or 500 mg/m²/dose intravenously.
    • If necessary, the dose may be given again every six hours.
    • The usual adult dose is 1,000 to 2,000 mg/dose.
    • The maximum total dose is 1.8 g/m² for three days.
    • The injection is not recommended for longer than three days in adults.

Pregnancy Risk Category: C

  • It has not yet been tested in pregnant animals or humans.
  • In utero exposure has been linked to congenital and fetal abnormalities.

Use of methocarbamol while breastfeeding

  • It is unknown if the drug will be excreted into breastmilk.
  • Manufacturers recommend that lactating women use the drug with caution.

Methocarbamol (Robaxin) Dose in Kidney Disease:

  • Patients with kidney disease should not be given dose adjustments according to the manufacturer's label.
  • Patients with kidney disease should not be given the injection because it contains polyethylene glycol.

Methocarbamol (Robaxin) Dose in Liver disease:

  • In the manufacturer's labeling, adjustment in the dose has not been recommended.
  • However, the half-life of the drug is increased in patients with cirrhosis.

Side effects of Methocarbamol (Robaxin):

  • Cardiovascular:

    • Bradycardia
    • Flushing
    • Hypotension
    • Syncope
    • Thrombophlebitis
  • Central Nervous System:

    • Amnesia
    • Ataxia
    • Confusion
    • Dizziness
    • Drowsiness
    • Headache
    • Insomnia
    • Metallic Taste
    • Sedation
    • Seizure
    • Vertigo
  • Dermatologic:

    • Pruritus
    • Skin Rash
    • Urticaria
  • Gastrointestinal:

    • Dyspepsia
    • Nausea
    • Vomiting
  • Hematologic & Oncologic:

    • Leukopenia
  • Hepatic:

    • Cholestatic Jaundice
    • Jaundice
  • Hypersensitivity:

    • Anaphylaxis
    • Angioedema
    • Hypersensitivity Reaction
  • Local:

    • Local Skin Exfoliation (Injection)
    • Pain At Injection Site
  • Ophthalmic:

    • Blurred Vision
    • Conjunctivitis
    • Diplopia
    • Nystagmus
  • Respiratory:

    • Nasal Congestion
  • Miscellaneous:

    • Fever

Contraindications to Methocarbamol (Robaxin):

  • Allergy reactions to any component of the drug or the drug itself
  • Injection formulation for kidney disease

Warnings and precautions

  • Depression in the CNS:

    • It can cause depression in the central nervous system. 
    • People who are required to be alert and those who drive or operate heavy machinery should be cautious about using the drug.
  • Hepatic impairment

    • Patients with liver disease have a lower drug-binding protein to plasma proteins, which results in decreased drug clearance and a longer half-life.
  • Renal impairment

    • Patients with kidney impairment should avoid intravenous injections.
  • Seizure disorder

    • Patients with seizure disorders should avoid intravenous administration.
    • Patients with seizure disorders may need to be cautious when taking oral formulation.

Methocarbamol: Drug Interaction

Risk Factor C (Monitor therapy)

Alcohol (Ethyl)

Alcohol's CNS depressing effect may be amplified by CNS depressants (Ethyl).


CNS depressants may have an enhanced CNS depressant impact.

Botulinum Toxin-Containing Products

Centrally acting muscle relaxants may intensify the harmful/toxic effects of products containing  botulinum  toxin. In particular, there may be a greater likelihood of developing muscle  weakness.


Brexanolone's CNS depressing effects may be amplified by other CNS depressants.

Brimonidine (Topical)

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.

Chlorphenesin Carbamate

CNS depressants may have an enhanced CNS depressant impact.

CNS Depressants

CNS depressants may have an enhanced CNS depressant impact.

Dimethindene (Topical)

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact. Management: The producer of the pregnancy-safe drug Diclegis (doxylamine/pyridoxine) particularly advises against combining it with other CNS depressants.


CNS depressants may have an enhanced CNS depressant impact.


Could make methocarbamol's negative or hazardous effects worse.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.

Kava Kava

CNS depressants may have an enhanced CNS depressant impact.


May enhance the adverse/toxic effect of Methocarbamol.

Magnesium Sulfate

CNS depressants may have an enhanced CNS depressant impact.


CNS Depressants may enhance the sedative effect of MetyroSINE.

Minocycline (Systemic

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.


Piribedil's CNS depressing effects may be enhanced by other CNS depressants.


The sedative effects of pramipexole might be enhanced by CNS depressants.


.Methocarbamol may reduce Pyridostigmine's therapeutic effect.


The sedative effects of CNS depressants may increase those of ROPINIRole.


Rotigotine's sedative effects may be boosted by CNS depressants.


CNS depressants' harmful or toxic effects could be increased. Particularly, drowsiness and lightheadedness could be  worsened.

Selective Serotonin Reuptake Inhibitors

Selective serotonin reuptake inhibitors may have a worsened or more hazardous effect when taken with CNS  depressants. Particularly, there may be an increased risk of psychomotor impairment.


CNS depressants may have an enhanced CNS depressant impact.

Tetrahydrocannabinol and Cannabidiol

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.

Risk Factor D (Consider therapy modification)


Blonanserin's CNS depressing effects may be enhanced by other CNS depressants.


The CNS depressing impact of buprenorphine may be enhanced by CNS depressants. Treatment: If a patient  has a high risk of abusing or injecting themselves with buprenorphine, consider reducing  the doses of other  CNS depressants and avoiding such medications. Buprenorphine should be started at lower doses in individuals  who are currently taking CNS depressants.


CNS depressants may have an enhanced CNS depressant impact. Management: Keep a close eye out for signs of  severe CNS depression. If such a combination is required, it should be taken at a dose that has been suitably  lowered,  according to the instructions for chlormethiazole.


CNS depressants may have an enhanced CNS depressant impact. Consider lowering the dosage of droperidol or  other CNS drugs (such as opioids or barbiturates) when they are used concurrently. In separate  drug interaction  monographs, exceptions to this monograph are covered in more detail.


Flunitrazepam's CNS depressing effects may be enhanced by other CNS depressants.


The CNS depressive action of HYDROcodone may be enhanced by CNS depressants. Management: Whenever  feasible,  refrain from using hydrocodone and benzodiazepines or other CNS depressants concurrently. Only in the  event that other treatment choices are insufficient should these medications be combined. Limit the  duration  and dosage of each medicine when used together.


CNS depressants may have an enhanced CNS depressant impact. Management: Due to the possibility of additive  CNS  depressant effects when lemborexant and concurrent CNS depressants are administered concurrently,  dosage modifications may be required. Effects of CNS depressants must be closely monitored.


The CNS depressing action of methotrimeprazine may be enhanced by CNS depressants. The CNS depressant action  of  CNS  Depressants may be strengthened by methotrimeprazine. Management: Start concurrent methotrimeprazine  therapy while  reducing  the adult dose of CNS depressants by 50%. Only once a clinically effective dose of  methotrimeprazine  has been established  should additional CNS  depressant dosage modifications be made.

Opioid Agonists

Opioid agonists' CNS depressing effects may be amplified by CNS depressants. Management: When at all possible,  refrain from using benzodiazepines or other CNS depressants concurrently with opioid agonists. Only in the  event that other treatment choices are insufficient should these medications be combined. Limit the duration and  dosage of each medicine when used together.


The CNS depressing effects of OxyCODONE may be enhanced by CNS depressants. Management: Whenever  feasible,  refrain from using oxycodone and benzodiazepines or other CNS depressants concurrently. Only in the  event  that other treatment choices are insufficient should these medications be combined. Limit the duration  and dosage of each medicine when used together.


CNS depressants may have an enhanced CNS depressant impact. Treatment: Until they have experience using  the combination, patients  taking perampanel along  with any other medication that has CNS depressive  effects  should avoid complex and high-risk activities, especially those like driving that call for awareness and  coordination.

Sodium Oxybate

CNS depressants may have an enhanced CNS depressant impact. Management: Take into account substitutes for  combined use. Reduce the doses of one or more medications when simultaneous use is necessary. It is not  advised to use sodium oxybate with alcoholic beverages or hypnotic sedatives.


Suvorexant's CNS depressing effects may be amplified by other CNS depressants. Treatment: Suvorexant and/or  any other CNS depressant dosage reduction may be required. Suvorexant shouldn't be taken with alcohol,  and it  shouldn't be taken for sleeplessness with any other medication either.


CNS depressants may have an enhanced CNS depressant impact. Treatment: When feasible, refrain from using  tapentadol and benzodiazepines or other CNS depressants simultaneously. Only in the event that other  treatment  choices are insufficient should these medications be combined. Limit the duration and dosage of each medicine  when used together.


May intensify the negative or harmful effects of muscle relaxants (Centrally Acting). Management: If tolperisone is  used  with  other centrally acting muscle relaxants, watch for signs of increased sedation or CNS effects. If these  medications  are taken together, think about lowering the tolperisone dosage.


CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol.

Risk Factor X (Avoid combination)

Azelastine (Nasal)

Azelastine's CNS depressing impact may be amplified by CNS depressants (Nasal).


CNS depressants may have an enhanced CNS depressant impact.


Azelastine's CNS depressing impact may be amplified by CNS depressants (Nasal).


CNS depressants may have an enhanced CNS depressant impact.


The CNS depressing effects of paraldehyde may be enhanced by CNS depressants.


The CNS depressing effect of thalidomide may be enhanced by CNS depressants.


Monitoring parameters:

Monitor the injection site closely for extravasation

  • Monitor the site for bradycardia and hypotension after intravenous administration.

How to administer Methocarbamol (Robaxin)?

Solution for injection:

  • Intramuscular Injection
    • It should be administered in the gluteal area. Each gluteal area may receive a maximum of 5mL.
  • Intravenous injection:
    • Maximum rate of injection should not exceed 3mL/minute
    • You can administer the injection undiluted or diluted.
    • Extravasation should be monitored at the injection site.
    • It is important to administer the injection intravenously when the patient lies down.
    • After the infusion, you should remain in a recumbent position for between 10 and 15 minutes.


  • If necessary, the tablets can be broken up and mixed with liquids or food.

Mechanism of action of Methocarbamol (Robaxin):

It causes the depression of central nervous system resulting in skeletal muscle relaxation.

The onset of action after oral administration:

  • Muscle relaxation: About 30 minutes

Protein binding:

  • 46% to 50%


  • It is metabolized in the liver via dealkylation and hydroxylation

Half-life elimination:

  • 1 to 2 hours

Time to peak serum concentration after oral administration:

  • 1 to 2 hours


  • It is excreted in the urine primarily as metabolites.

International Brands of Methocarbamol:

  • Robaxin
  • Robaxin-750
  • Methocarbamol Omega
  • PMS-Methocarbamol
  • Robaximol
  • Bolaxin
  • Carbamol
  • Lumirelax
  • Manobaxine
  • Methocarbamol
  • Metocamol
  • Mibelaxol
  • Miowas
  • Musxan
  • Myomethol
  • Myorexin Inj
  • New-Rexan
  • Ortoton
  • Rebamol
  • Rexivin
  • Robinax

Methocarbamol Brand Names in Pakistan:

No Brands Available in Pakistan.


NO Comments Found