Skelaxin (metaxalone) - What You Need to Know

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Skelaxin (metaxalone) is used to treat muscle pain and stiffness elated to acute, painful musculoskeletal conditions such as strains, sprains, or other injuries. It is often used in combination with rest, physical therapy. 

Chemically, the formulation of metaxalone is given as 5-[(3,5- (dimethylphenoxy) methyl]-2-oxazolidinone with an empirical formula of C12H15N03 and molecular weight of 221.25. The mode of action of this drug has not been clearly identified, but experts believe the drug works by blocking nerve impulses or pain sensations in the brain.


Metaxolone is available by prescription only and may be given to patients with the following conditions:

Recommended Dosage

The recommended dose of Metaxalone for adults and children over 12 years of age is one 800 mg tablet three to four times a day. It is important not to take more of this medication than you doctor prescribed. Dangerous side effects can occur if you take too much. 

Metaxalone is absorbed in the small intestine and is metabolized by the liver and excreted in urine as unidentified metabolites.

Who Shouldn't Take Metaxolone

While Metaxalone has been found to be safe in most patients, certain patients should not take it. These include patients with any known hypersensitivity to any components of the drug; those with a known tendency to drug-induced, hemolytic, or other anemias; and those with significantly impaired renal or hepatic function.

In addition, patients who consume alcohol should be advised that metaxalone may enhance the effects of alcohol and other CNS depressants. Metaxalone may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle, especially when used with alcohol or other CNS depressants.

Safe use of metaxalone has not been established with regard to possible adverse effects upon fetal development. Therefore, metaxalone tablets should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgement of the physician the potential benefits outweigh the possible hazards.

It is not known whether this drug is secreted in human milk. As a general rule, nursing should not be undertaken while a patient is on a drug since many drugs are excreted in human milk. Pediatric use, safety and effectiveness in children 12 years of age and below have not been established.

Side Effects of Metaxolone

Although rare, anaphylactoid reactions have been reported with metaxalone. Signs of an allergic reaction include: 

  • Hives
  • Difficulty breathing
  • Swelling of the face, lips, tongue, or throat
  • Drowsiness and dizziness
  • Nausea
  • Vomiting

The most frequent reactions to metaxalone include:

  • CNS: drowsiness, dizziness, headache, and nervousness or “irritability”
  • Digestive: nausea, vomiting, gastrointestinal upset
  • Immune system: hypersensitivity reaction, rash with or without pruritus
  • Hematologic: leukopenia, hemolytic anemia
  • Hepatobiliary: jaundice


U.S. Food and Drug Administration, NDA 13-217/S-036, Revised: August, 2002

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