Robaxin (Methocarbamol) 500 mg and 750 mg Tablets: Prescription Central-Acting Muscle Relaxant for Acute Musculoskeletal Spasm

Information last reviewed: May 2026 — for educational purposes only.

Robaxin (methocarbamol) is a prescription central-acting skeletal muscle relaxant used as an adjunct to rest and physical therapy for the relief of discomfort associated with acute, painful musculoskeletal conditions such as muscle strain, back spasm, and neck spasm. Methocarbamol does not act directly on skeletal muscle fibres or the motor end plate; its muscle-relaxing effects are believed to arise from general CNS (central nervous system) depression at the spinal cord and subcortical levels, reducing polysynaptic reflexes that sustain muscle spasm.

What Is Methocarbamol?

Methocarbamol is a carbamate derivative of guaifenesin (the chest congestion expectorant). While guaifenesin itself has weak muscle-relaxant properties, methocarbamol has much more potent CNS depressant activity. It was first approved in the 1950s and has a well-established safety record for short-term use in otherwise healthy adults. Methocarbamol is one of the less sedating muscle relaxants in its class compared to cyclobenzaprine or carisoprodol (Soma), though sedation still occurs — particularly at higher doses — and patients should exercise caution with driving and machinery.

An injectable formulation (methocarbamol 100 mg/mL solution) is also available for hospital or clinic use in patients with severe spasm who cannot take oral medications, particularly in tetanus management.

Is Methocarbamol Available Over the Counter?

Methocarbamol is prescription-only in the United States. There is no OTC oral muscle relaxant approved for spasm relief. Patients with acute back or neck spasm should consult a physician who may prescribe methocarbamol alongside an NSAID or analgesic as part of a short-course multimodal plan. The injection form requires administration in a clinical setting.

Tablet Strengths and Dosing

• 500 mg tablets — initial dosing: 1,500 mg (three 500 mg tablets) four times daily (QID), or 500–750 mg three times daily (TID) once initial severe spasm begins to ease
• 750 mg tablets — higher-strength tablet; allows fewer tablets per dose; 750 mg–1,500 mg three or four times daily

Typical dosing for acute spasm: 1.5 g four times daily for the first 48–72 hours, then reduced to a maintenance dose of 750 mg four times daily or 1,500 mg three times daily. The total daily dose rarely exceeds 8 g (16 × 500 mg tablets). Treatment courses are generally 2–3 weeks for acute musculoskeletal conditions; prolonged use is not routinely recommended.

Methocarbamol should be taken with food if GI upset occurs. Due to CNS depression, patients should avoid concurrent alcohol, benzodiazepines, or other CNS depressants. Patients with myasthenia gravis should not use methocarbamol, as it may worsen neuromuscular blockade.

Price of Generic Methocarbamol

Generic methocarbamol 500 mg and 750 mg tablets are among the least expensive muscle relaxants available by prescription in the US. A 30-day supply at typical dosing is inexpensive with insurance, and GoodRx or similar pharmacy discount programs reduce the out-of-pocket cost substantially even without insurance coverage.

Frequently Asked Questions

How does methocarbamol compare to cyclobenzaprine (Flexeril)?

Both are central-acting muscle relaxants with sedative effects. Cyclobenzaprine tends to cause more pronounced drowsiness than methocarbamol, particularly at the 10 mg dose, and has anticholinergic effects (dry mouth, urinary retention) more prominent than methocarbamol. For patients who cannot tolerate cyclobenzaprine's sedation, methocarbamol may be better tolerated. Efficacy for acute spasm is broadly similar between them.

Can methocarbamol be taken long-term for chronic back pain?

Methocarbamol is intended for short-term use only (typically 2–3 weeks). Evidence for benefit in chronic musculoskeletal pain is limited, and long-term use may lead to dependence in susceptible individuals and chronic CNS depression. For chronic back pain, physical therapy, low-impact exercise, and, where indicated, anti-inflammatory medications or referral to a pain specialist are preferred over long-term muscle relaxant use.

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