Methocarbamol
Skeletal muscle relaxants and spasmolytics
Skeletal muscle relaxants and spasmolytics
An older muscle relaxant whose effect seems to come from general sedation; used briefly for acute musculoskeletal pain.
Quick facts
- Group
- Skeletal muscle relaxants and spasmolytics
- Target
- No specific target known (general CNS depression)
- Used for
- Adjunct to rest
- Key effects
- Drowsiness and dizziness · Headache · Flushing
- Monitor
- Sedation and fall risk · Short duration of use
- ATC
- M03BA03
No doses: the clinician sets them by the current guideline.
Mechanism of action
How methocarbamol works in humans has not been established. It has no direct action on the contractile mechanism of striated muscle, the motor end plate or the nerve fibre; its benefit is thought to come from general central nervous system depression and sedation.
- Acts in the central nervous system, not on muscle
- General sedation reduces the perception of spasm and pain
Indications
- Adjunct to rest and physical therapy for acute, painful musculoskeletal conditions (e.g., acute low back pain) Mechanical low back pain →
Adverse effects
Common
- Drowsiness and dizziness
- Headache, nausea and vomiting
- Flushing, low blood pressure and slow heart rate
Contraindications
- Hypersensitivity to methocarbamol
Key interactions
- Alcohol and other CNS depressants
- Additive sedation
- Pyridostigmine (myasthenia gravis)
- Methocarbamol may weaken its effect
What is monitored
- Sedation and fall risk
- Short duration of use; older adults usually receive safer alternatives
Pregnancy and breastfeeding
Safety in pregnancy is not established and there are reports of fetal abnormalities; it is avoided, especially early in pregnancy, unless clearly needed.
Nursing care
- Warn about drowsiness, driving and alcohol
- Ask about pregnancy and myasthenia gravis
- It may interfere with some urine screening tests (5-HIAA, VMA)
Pharmacokinetics
- Metabolism
- Dealkylation, hydroxylation and conjugation; clearance is much lower in cirrhosis
- Elimination
- Metabolites in the urine
- Half-life
- About 1 to 2 hours
Test yourself
Think of the answer, then tap the question to see it.
Does methocarbamol act directly on skeletal muscle?
No; its effect is thought to come from general CNS depression.
Which myasthenia gravis drug can methocarbamol weaken?
Pyridostigmine.
Which organ impairment most prolongs methocarbamol's half-life?
Liver cirrhosis.
Connections
← Back to the class: Skeletal muscle relaxants and spasmolytics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - METHOCARBAMOL tablet (DailyMed (U.S. National Library of Medicine), 2026); Methocarbamol: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.