METHOCARBAMOL: 2,201 Adverse Event Reports & Safety Profile
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Drug Class: Centrally-mediated Muscle Relaxation [PE] · Route: ORAL · Manufacturer: PD-Rx Pharmaceuticals, Inc. · FDA Application: 011011 · HUMAN PRESCRIPTION DRUG · FDA Label: Available
Patent Expires: Oct 9, 2044 · First Report: 2003 · Latest Report: 20250720
What Are the Most Common METHOCARBAMOL Side Effects?
All METHOCARBAMOL Side Effects by Frequency
| Side Effect | Reports | % of Total | Deaths | Hosp. |
|---|---|---|---|---|
| Drug ineffective | 294 | 13.4% | 1 | 138 |
| Completed suicide | 277 | 12.6% | 276 | 99 |
| Toxicity to various agents | 166 | 7.5% | 133 | 90 |
| Drug hypersensitivity | 162 | 7.4% | 2 | 9 |
| Drug dependence | 130 | 5.9% | 10 | 90 |
| Drug abuse | 121 | 5.5% | 30 | 75 |
| Hypertension | 119 | 5.4% | 31 | 68 |
| Off label use | 105 | 4.8% | 6 | 70 |
| Respiratory depression | 104 | 4.7% | 0 | 90 |
| Nausea | 95 | 4.3% | 4 | 37 |
| Product use issue | 90 | 4.1% | 5 | 80 |
| Dizziness | 89 | 4.0% | 15 | 30 |
| Product prescribing error | 87 | 4.0% | 5 | 76 |
| Pain | 82 | 3.7% | 6 | 20 |
| Somnolence | 81 | 3.7% | 5 | 32 |
| Intentional overdose | 78 | 3.5% | 7 | 61 |
| Muscle spasms | 71 | 3.2% | 1 | 29 |
| Contusion | 69 | 3.1% | 14 | 38 |
| Overdose | 69 | 3.1% | 19 | 46 |
| Headache | 67 | 3.0% | 14 | 25 |
Who Reports METHOCARBAMOL Side Effects? Age & Gender Data
Gender: 68.7% female, 31.3% male. Average age: 49.7 years. Most reports from: US. View detailed demographics →
Is METHOCARBAMOL Getting Safer? Reports by Year
| Year | Reports | Deaths | Hosp. |
|---|---|---|---|
| 2003 | 2 | 0 | 0 |
| 2004 | 1 | 0 | 1 |
| 2006 | 2 | 1 | 0 |
| 2007 | 2 | 0 | 0 |
| 2008 | 16 | 2 | 9 |
| 2009 | 1 | 0 | 0 |
| 2010 | 1 | 0 | 1 |
| 2011 | 10 | 1 | 1 |
| 2012 | 8 | 3 | 1 |
| 2013 | 5 | 0 | 0 |
| 2014 | 51 | 2 | 19 |
| 2015 | 63 | 30 | 10 |
| 2016 | 54 | 17 | 15 |
| 2017 | 64 | 13 | 31 |
| 2018 | 60 | 12 | 27 |
| 2019 | 115 | 22 | 63 |
| 2020 | 92 | 29 | 40 |
| 2021 | 69 | 26 | 22 |
| 2022 | 44 | 13 | 23 |
| 2023 | 95 | 57 | 21 |
| 2024 | 44 | 3 | 12 |
| 2025 | 42 | 11 | 15 |
What Is METHOCARBAMOL Used For?
| Indication | Reports |
|---|---|
| Product used for unknown indication | 1,023 |
| Muscle spasms | 148 |
| Back pain | 128 |
| Pain | 108 |
| Muscle relaxant therapy | 44 |
| Suicide attempt | 34 |
| Child abuse | 25 |
| Fibromyalgia | 23 |
| Neck pain | 21 |
| Hypertension | 20 |
METHOCARBAMOL vs Alternatives: Which Is Safer?
Other Drugs in Same Class: Centrally-mediated Muscle Relaxation [PE]
Official FDA Label for METHOCARBAMOL
Official prescribing information from the FDA-approved drug label.
Drug Description
DESCRIPTION Methocarbamol Tablets USP, a carbamate derivative of guaifenesin, is a central nervous system (CNS) depressant with sedative and musculoskeletal relaxant properties. The chemical name of methocarbamol is 3 - (2-methoxyphenoxy) -1, 2- propanediol 1-carbamate and has the empirical formula C 11 H 15 NO 5 . Its molecular weight is 241.24. The structural formula is shown below. Methocarbamol is a white powder, sparingly soluble in water and chloroform, soluble in alcohol (only with heating) and propylene glycol, and insoluble in benzene and n-hexane.
Methocarbamol
Tablets USP, 500 mg is available as a light orange colored, round, film-coated tablets, engraved with 'B134' on one side and scored on the other side, containing 500 mg of methocarbamol, USP for oral administration. The inactive ingredients present are corn starch, low substituted hydroxypropyl cellulose, hydroxyprolyl cellulose, sodium starch glycolate, povidone, sodium lauryl sulfate, colloidal silicon dioxide, stearic acid, magnesium stearate, and purified water.
Methocarbamol
Tablets USP, 500 mg contains Opadry 13H530000 (Orange) (hypromellose, titanium dioxide, propylene glycol, FD&C yellow #6/Sunset Yellow FCF Aluminum Lake, polysorbate 20) as coating material.
Methocarbamol
Tablets USP, 750 mg is available as an orange colored, capsule shaped, film coated tablets, engraved with 'B135' on one side and plain on the other side, containing 750 mg of methocarbamol, USP for oral administration. It contains Opadry 13H530001 (Orange) as coating material. The inactive ingredients present are corn starch, low substituted hydroxypropyl cellulose, hydroxyprolyl cellulose, sodium starch glycolate, povidone, sodium lauryl sulfate, colloidal silicon dioxide, stearic acid, magnesium stearate, and purified water.
Methocarbamol
Tablets USP, 750 mg contain Opadry 13H530001 (Orange) (hypromellose, titanium dioxide, propylene glycol, D&C Yellow #10 Aluminum Lake, FD&C yellow #6/Sunset Yellow FCC Aluminum Lake, polysorbate 20) as coating material. structure.jpg
FDA Approved Uses (Indications)
AND USAGE ATMEKSI (methocarbamol) oral suspension is a muscle relaxant indicated as: an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions in patients 16 and older.
1.1 Acute, painful musculoskeletal conditions. ATMEKSI is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions in patients 16 and older.
1.1 Acute, painful musculoskeletal conditions. ATMEKSI is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions in patients 16 and older.
Dosage & Administration
DOSAGE AND ADMINISTRATION: For Intravenous and Intramuscular Use Only . Total adult dosage should not exceed 30 mL (3 vials) a day for more than 3 consecutive days except in the treatment of tetanus. If the condition persists, a like course may be repeated after a drug-free interval of 48 hours. Dosage and frequency of injection should be based on the severity of the condition being treated and therapeutic response noted. For the relief of symptoms of moderate degree, one dose of 1 gram (one 10 mL vial) may be adequate. Ordinarily this injection need not be repeated, as the administration of the oral form will usually sustain the relief initiated by the injection. For the severest cases or in postoperative conditions in which oral administration is not feasible, additional doses of 1 gram may be repeated every 8 hours up to a maximum of 3 g/day for no more than 3 consecutive days. Directions for Intravenous Use Methocarbamol Injection may be administered undiluted directly into the vein at a maximum rate of three mL per minute. It may also be added to an intravenous drip of Sodium Chloride Injection (Sterile Isotonic Sodium Chloride Solution for Parenteral Use) or five percent Dextrose Injection (Sterile 5 percent Dextrose Solution); one vial given as a single dose should not be diluted to more than 250 mL for intravenous infusion. AFTER MIXING WITH INTRAVENOUS INFUSION FLUIDS, DO NOT REFRIGERATE. Care should be exercised to avoid vascular extravasation of this hypertonic solution, which may result in thrombophlebitis. It is preferable that the patient be in a recumbent position during and for at least 10 to 15 minutes following the injection. Directions for Intramuscular Use When the intramuscular route is indicated, not more than five mL (one-half vial) should be injected into each gluteal region. The injections may be repeated at eight hour intervals, if necessary. When satisfactory relief of symptoms is achieved, it can usually be maintained with tablets.
Not
Recommended for Subcutaneous Administration.
Special
Directions for Use in Tetanus There is clinical evidence which suggests that methocarbamol may have a beneficial effect in the control of the neuromuscular manifestations of tetanus. It does not, however, replace the usual procedure of debridement, tetanus antitoxin, penicillin, tracheotomy, attention to fluid balance, and supportive care.
Methocarbamol
Injection should be added to the regimen as soon as possible. For adults: Inject one or two vials directly into the tubing of the previously inserted indwelling needle. An additional 10 mL or 20 mL may be added to the infusion bottle so that a total of up to 30 mL (three vials) is given as the initial dose (see PRECAUTIONS ). This procedure should be repeated every six hours until conditions allow for the insertion of a nasogastric tube. Crushed methocarbamol tablets suspended in water or saline may then be given through this tube. Total daily oral doses up to 24 grams may be required as judged by patient response. For pediatric patients: A minimum initial dose of 15 mg/kg or 500 mg/m 2 is recommended. This dosage may be repeated every six hours, if required. The total dose should not exceed 1.8 g/m 2 for 3 consecutive days. The maintenance dosage may be given by injection into tubing or by intravenous infusion with an appropriate quantity of fluid. See directions for intravenous use.
Contraindications
CONTRAINDICATIONS: Methocarbamol Injection should not be administered to patients with known or suspected renal pathology. This caution is necessary because of the presence of polyethylene glycol 300 in the vehicle. A much larger amount of polyethylene glycol 300 than is present in recommended doses of Methocarbamol Injection is known to have increased pre-existing acidosis and urea retention in patients with renal impairment. Although the amount present in this preparation is well within the limits of safety, caution dictates this contraindication.
Methocarbamol
Injection is contraindicated in patients hypersensitive to methocarbamol or to any of the injection components.
Known Adverse Reactions
REACTIONS The following serious adverse reaction is described elsewhere in the labeling: Interactions with CNS Depressants and Alcohol [ see Warnings and Precautions (5.1) ] The following adverse reactions associated with the use of methocarbamol have been identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Adverse reactions reported with the administration of methocarbamol include: Body as a whole : Anaphylactic reaction, angioneurotic edema, fever, headache. Cardiovascular system: Bradycardia, flushing, hypotension, syncope, thrombophlebitis. Digestive system: Dyspepsia, jaundice (including cholestatic jaundice), nausea and vomiting. Hemic and lymphatic system: Leukopenia.
Immune
System: Hypersensitivity reactions. Nervous system: Amnesia, confusion, diplopia, dizziness or lightheadedness, drowsiness, insomnia, mild muscular incoordination, nystagmus, sedation, seizures (including grand mal), vertigo. Skin and special senses: Blurred vision, conjunctivitis, nasal congestion, metallic taste, pruritus, rash, urticaria. Body: Anaphylactic reaction, angioneurotic edema, fever, headache ( 6 ) Cardiovascular system: Bradycardia, flushing, hypotension, syncope, thrombophlebitis ( 6 ) Digestive system: Dyspepsia, jaundice (including cholestatic jaundice), nausea and vomiting ( 6 ) Hemic and lymphatic system: Leukopenia ( 6 ) Immune system: Hypersensitivity reactions ( 6 ) Nervous system: Amnesia, confusion, diplopia, dizziness or lightheadedness, drowsiness, insomnia, mild muscular incoordination, nystagmus, sedation, seizures (including grand mal), vertigo ( 6 ) Skin and special senses: Blurred vision, conjunctivitis, nasal congestion, metallic taste, pruritus, rash and urticaria ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Rosemont Pharmaceuticals, LLC. at 1-844-638-2235 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .
Warnings
Warnings and Precautions Since methocarbamol may possess a general CNS depressant effect, patients receiving Methocarbamol Tablets USP, 500 mg or 750 mg should be cautioned about combined effects with alcohol and other CNS depressants. Safe use of Methocarbamol Tablets USP, 500 mg and 750 mg has not been established with regard to possible adverse effects upon fetal development. There have been reports of fetal and congenital abnormalities following in utero exposure to methocarbamol. Therefore, Methocarbamol Tablets USP, 500 mg and 750 mg should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgment of the physician the potential benefits outweigh the possible hazards (see PRECAUTIONS, PREGNANCY).
Use In Activities Requiring Mental
Alertness Methocarbamol may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle. Patients should be cautioned about operating machinery, including automobiles, until they are reasonably certain that methocarbamol therapy does not adversely affect their ability to engage in such activities. Information for Patients Patients should be cautioned that methocarbamol may cause drowsiness or dizziness, which may impair their ability to operate motor vehicles or machinery. Because methocarbamol may possess a general CNS-depressant effect, patients should be cautioned about combined effects with alcohol and other CNS depressants.
Drug Interactions
See WARNINGS and PRECAUTIONS for interaction with CNS drugs and alcohol. Methocarbamol may inhibit the effect of pyridostigmine bromide. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving anticholinesterase agents.
Drug/Laboratory
Test Interactions Methocarbamol may cause a color interference in certain screening tests for 5-hydroxyindoleacetic acid (5-HIAA) using nitrosonaphthol reagent and in screening tests for urinary vanillylmandelic acid (VMA) using the Gitlow method. Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term studies to evaluate the carcinogenic potential of methocarbamol have not been performed. No studies have been conducted to assess the effect of methocarbamol on mutagenesis or its potential to impair fertility.
Pregnancy Teratogenic Effects Pregnancy
Category C Animal reproduction studies have not been conducted with methocarbamol. It is also not known whether methocarbamol can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity.
Methocarbamol
Tablets USP, 500 mg and 750 mg should be given to a pregnant woman only if clearly needed. Safe use Methocarbamol Tablets USP, 500 mg and 750 mg has not been established with regard to possible adverse effects upon fetal development. There have been reports of fetal and congenital abnormalities following in utero exposure to methocarbamol. Therefore, Methocarbamol Tablets USP, 500 mg and 750 mg should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgment of the physician the potential benefits outweigh the possible hazards (see WARNINGS).
Nursing Mothers
Methocarbamol and/or its metabolites are excreted in the milk of dogs; however, it is not known whether methocarbamol or its metabolites are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Methocarbamol Tablets USP, 500 mg or 750 mg is administered to a nursing woman.
Pediatric Use
Safety and effectiveness of Methocarbamol Tablets USP, 500 mg and 750 mg in pediatric patients below the age of 16 have not been established.
Precautions
PRECAUTIONS General As with other agents administered either intravenously or intramuscularly, careful supervision of dose and rate of injection should be observed. Rate of injection should not exceed 3 mL per minute - i.e., one 10 mL vial in approximately three minutes.
Since Methocarbamol
Injection is hypertonic, vascular extravasation must be avoided. A recumbent position will reduce the likelihood of side reactions. Blood aspirated into the syringe does not mix with the hypertonic solution. This phenomenon occurs with many other intravenous preparations. The blood may be injected with the methocarbamol, or the injection may be stopped when the plunger reaches the blood, whichever the physician prefers. The total dosage should not exceed 30 mL (three vials) a day for more than three consecutive days except in the treatment of tetanus. Caution should be observed in using the injectable form in patients with suspected or known seizure disorders. Information for Patients Patients should be cautioned that methocarbamol may cause drowsiness or dizziness, which may impair their ability to operate motor vehicles or machinery. Because methocarbamol may possess a general CNS-depressant effect, patients should be cautioned about combined effects with alcohol and other CNS depressants.
Drug Interactions
See WARNINGS and PRECAUTIONS for interaction with CNS drugs and alcohol. Methocarbamol may inhibit the effect of pyridostigmine bromide. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving anticholinesterase agents.
Drug/Laboratory
Test Interactions Methocarbamol may cause a color interference in certain screening tests for 5-hydroxyindoleacetic acid (5-HIAA) using nitrosonaphthol reagent and in screening tests for urinary vanillylmandelic acid (VMA) using the Gitlow method. Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term studies to evaluate the carcinogenic potential of methocarbamol have not been performed. No studies have been conducted to assess the effect of methocarbamol on mutagenesis or its potential to impair fertility.
Pregnancy Teratogenic
Effects-Pregnancy Category C Animal reproduction studies have not been conducted with methocarbamol. It is also not known whether methocarbamol can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity.
Methocarbamol
Injection should be given to a pregnant woman only if clearly needed. Safe use of Methocarbamol Injection has not been established with regard to possible adverse effects upon fetal development. There have been reports of fetal and congenital abnormalities following in utero exposure to methocarbamol. Therefore, Methocarbamol Injection should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgment of the physician the potential benefits outweigh the possible hazards (see WARNINGS ).
Nursing Mothers
Methocarbamol and/or its metabolites are excreted in the milk of dogs; however, it is not known whether methocarbamol or its metabolites are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Methocarbamol Injection is administered to a nursing woman.
Pediatric Use
Safety and effectiveness of Methocarbamol Injection in pediatric patients have not been established except in tetanus. See DOSAGE AND ADMINISTRATION , Special Directions for Use in Tetanus , For Pediatric Patients.
Drug Interactions
INTERACTIONS ATMEKSI may inhibit the effect of pyridostigmine bromide. Patients with myasthenia gravis should be monitored closely for symptoms of myasthenia gravis such as weakness. If symptoms of myasthenia gravis are observed, treatment with ATMEKSI should be stopped immediately ( 7.2 ) Laboratory test interference: Methocarbamol may cause color interference in the following screening tests: 5-hydroxyindoleacetic acid (using nitrosonaphthol reagent) and VMA (Giltow method) ( 7.3 )