Metaxalone Dosage

Medically reviewed by Drugs.com. Last updated on Apr 29, 2025.

Usual Adult Dose for Muscle Spasm

640 mg or 800 mg orally 3 to 4 times a day

Comments:

• Two 400 mg tablets or one 800 mg tablet are not substitutable on a mg-to-mg basis with 640 mg tablets. It is appropriate to switch:
• Only in patients who have been taking 640 mg tablets on an empty stomach
• Stop 640 mg tablets three times a day and start two 400 mg or one 800 mg three times a day on an empty stomach, OR stop 640 mg tablets four times a day and start two 400 mg or one 800 mg tablets four times a day on an empty stomach.
• Do not switch in patients taking this drug with food.

Use: Painful musculoskeletal conditions as an adjunct to rest, physical therapy, and other measures

Usual Pediatric Dose for Muscle Spasm

Children 13 years and older:
640 mg or 800 mg orally 3 to 4 times a day

Comments:

• Two 400 mg tablets or one 800 mg tablet are not substitutable on a mg-to-mg basis with 640 mg tablets. It is appropriate to switch:
• Only in patients who have been taking 640 mg tablets on an empty stomach
• Stop 640 mg tablets three times a day and start two 400 mg or one 800 mg three times a day on an empty stomach, OR stop 640 mg tablets four times a day and start two 400 mg or one 800 mg tablets four times a day on an empty stomach.
• Do not switch in patients taking this drug with food.

Use: Painful musculoskeletal conditions as an adjunct to rest, physical therapy, and other measures in patients 13 years of age and older

Renal Dose Adjustments

Mild to moderate renal dysfunction: Use with caution
Severe renal dysfunction: Contraindicated

Liver Dose Adjustments

Mild to moderate liver dysfunction: Use with caution
Severe liver dysfunction: Contraindicated

Precautions

CONTRAINDICATIONS:

• Hypersensitivity to the active component or any of the ingredients
• Known tendency to drug induced, hemolytic, or other anemias
• Severe renal or hepatic dysfunction

Safety and efficacy have not been established in patients younger than 13 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• Can be taken with or without food.

Storage requirements:

• Store at 20C to 25C (68F to 77F), with excursions permitted to 15C to 30C (59F to 86F)

General:

• Deaths by deliberate or accidental overdose have occurred with this drug, particularly in combination with antidepressants, and in combination with alcohol.

Monitoring:

• CNS symptoms and signs of serotonin syndrome, respiratory depression, or excessive sedation
• Report suspected adverse reactions to www.fda.gov/medwatch

Patient advice:

• Read the Patient Information and Instructions for Use.
• This drug 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.

See also:

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer