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Robaxin Side Effects

Generic Name: methocarbamol

Note: This page contains side effects data for the generic drug methocarbamol. It is possible that some of the dosage forms included below may not apply to the brand name Robaxin.

For the Consumer

Applies to methocarbamol: oral tablet

Other dosage forms:

As well as its needed effects, methocarbamol (the active ingredient contained in Robaxin) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking methocarbamol, check with your doctor immediately:

Incidence not known:
  • Abdominal or stomach pain
  • black, tarry stools
  • changes in skin color
  • chest pain or discomfort
  • chills
  • clay-colored stools
  • cough
  • dark urine
  • diarrhea
  • difficulty swallowing
  • dizziness
  • fast heartbeat
  • feeling of warmth
  • fever
  • headache
  • hives
  • itching
  • joint or muscle pain
  • large, hive-like swelling on face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • lightheadedness, dizziness, or fainting
  • loss of appetite
  • loss of bladder control
  • loss of consciousness
  • loss of memory
  • nausea
  • numbness or tingling of face, hands, or feet
  • pain, tenderness, or swelling of foot or leg
  • painful or difficult urination
  • problems with memory
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • redness and soreness of eyes
  • redness of the face, neck, arms, and occasionally, upper chest
  • relaxed and calm
  • shortness of breath
  • skin rash
  • sleepiness
  • slow or irregular heartbeat
  • sore throat
  • sores, ulcers, or white spots on lips or in mouth
  • swollen glands
  • tightness in chest
  • total body jerking
  • unpleasant breath odor
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vomiting of blood
  • wheezing
  • yellow eyes or skin

If any of the following symptoms of overdose occur while taking methocarbamol, get emergency help immediately:

Symptoms of overdose:
  • Shaking or jerking of one area or side of the body
  • sweating

Minor Side Effects

Some methocarbamol side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Incidence not known:
  • Acid or sour stomach
  • belching
  • double vision
  • drowsiness
  • feeling of constant movement of self or surroundings
  • heartburn
  • indigestion
  • mood or mental changes
  • seeing double
  • sensation of spinning
  • sleeplessness
  • stomach discomfort, upset, or pain
  • trouble sleeping
  • unable to sleep
  • uncontrolled eye movements

For Healthcare Professionals

Applies to methocarbamol: injectable solution, oral tablet


Cardiovascular side effects have included syncope, hypotension, and bradycardia.[Ref]

Nervous system

Nervous system side effects have included dizziness, lightheadedness, vertigo, headache, drowsiness, fainting, and mild muscular incoordination. Convulsions have been reported with intravenous administration, especially in patients with a history of epilepsy.[Ref]


Dermatologic side effects have included urticaria, pruritus, rash, sloughing, thrombophlebitis, and pain at the injection site.[Ref]


Ocular side effects have included blurred vision, conjunctivitis, nystagmus, and diplopia.[Ref]


Respiratory side effects have included nasal congestion, bronchospasm, and anaphylaxis.[Ref]


Gastrointestinal side effects have included gastrointestinal upset, anorexia, and adynamic ileus.[Ref]


Other side effects have included metallic taste and fever.

Effects on lab tests have included a possible color interference in certain screening tests for 5-hydroxyindoleacetic acid (5-HIAA) and vanillylmandelic acid (VMA).[Ref]


Hematologic side effects have included hemolysis, particularly with intravenous injection.[Ref]


Methocarbamol (the active ingredient contained in Robaxin) vials for injection contain polyethylene glycol 300 (PEG 300). Larger amounts of PEG 300 can increase preexisting renal acidosis and urea retention in patients with renal insufficiency.[Ref]

Renal side effects including urine discoloration (black, blue, brown, or green) have been reported after oral administration in some patients.[Ref]


General side effects have included angioneurotic edema.[Ref]


1. "Product Information. Robaxin Injectable (methocarbamol)." Whitehall-Robbins, Madison, NJ.

2. "Multum Information Services, Inc. Expert Review Panel"


It is possible that some side effects of Robaxin may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.