Flexeril vs. Robaxin

See how Flexeril and Robaxin compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Flexeril (cyclobenzaprine) and Robaxin (methocarbamol) both treat acute muscle spasm as an add-on to rest and physical therapy, not as standalone treatments.

  • Flexeril tends to cause more sedation and dry mouth because it is chemically related to tricyclic antidepressants, while Robaxin's side effects are generally milder but less precisely quantified in its label.

  • Robaxin also comes as an injectable used in tetanus management, while Flexeril is only available as an oral tablet.

Flexeril vs. Robaxin Drug Summary

Flexeril

Flexeril (cyclobenzaprine) is a tricyclic-amine skeletal muscle relaxant used short term for muscle spasm from acute musculoskeletal injuries. It works in the brain and spinal cord, not directly on muscle tissue, and is taken as an oral tablet three times a day for no more than two to three weeks.

Robaxin

Robaxin (methocarbamol) is a carbamate-class skeletal muscle relaxant used for the same kind of acute muscle spasm and discomfort. It comes as an oral tablet or an injectable solution, with the injectable form also used to support tetanus treatment.

Flexeril vs. Robaxin Side Effects

Flexeril

Most common
drowsiness (up to 39%)
dry mouth (up to 27%)
dizziness (up to 11%)
fatigue (up to 6%)

Robaxin

Most common
drowsiness (rate not specified in labeling)
dizziness or lightheadedness (rate not specified in labeling)
headache (rate not specified in labeling)
nausea (rate not specified in labeling)

Flexeril vs. Robaxin Dosage

Flexeril

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 5 mg three times daily At the start
Maximum dose 10 mg three times daily If needed
Dose changes 1 increase As tolerated

Robaxin

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 1500 mg four times daily Days 1-3
Maximum dose 1000 mg IM/IV per dose If needed
Dose changes 2 increases Every 3 days

Flexeril vs. Robaxin Indications

Flexeril

Flexeril is FDA-approved as an add-on to rest and physical therapy for muscle spasm caused by acute musculoskeletal conditions like a back strain. It is not approved for spasticity from conditions like cerebral palsy or spinal cord injury. It is sometimes used off-label for fibromyalgia pain and sleep symptoms.

  • Acute muscle spasm from musculoskeletal injury

  • Used alongside rest and physical therapy, not alone

  • Off-label: fibromyalgia pain and sleep symptoms

  • Not for spasticity from CNS disease

Robaxin

Robaxin is FDA-approved as an add-on to rest and physical therapy for discomfort from acute, painful musculoskeletal conditions. Its injectable form also has an approved role as adjunctive therapy in tetanus management. It is not approved for long-term or chronic pain management.

  • Acute muscle spasm and discomfort from injury

  • Used alongside rest and physical therapy, not alone

  • Injectable form: adjunct therapy for tetanus

  • Not approved for children under 16

Flexeril vs. Robaxin Pros and Cons

Flexeril

Flexeril has well-defined side effect rates from its FDA label, which makes it easier to counsel patients on what to expect. Its main tradeoff is stronger sedation, since it shares structural features with tricyclic antidepressants.

Pros

  • Side effect rates are clearly quantified in FDA labeling

  • Simple three-times-daily dosing with no titration schedule

  • Long track record of use since 1977

Cons

  • Higher rates of drowsiness and dry mouth than typical alternatives

  • Contraindicated with MAOIs, hyperthyroidism, and certain heart conditions

  • Only available as an oral tablet

Robaxin

Robaxin offers more dosing flexibility with both oral and injectable forms, including a role in tetanus care that Flexeril does not have. Its FDA label does not report specific side effect percentages, which makes its sedation profile harder to compare precisely.

Pros

  • Available as an injectable for situations needing IV/IM dosing

  • Not a federally controlled substance

  • Additional approved use as adjunct therapy in tetanus

Cons

  • Side effect rates are not quantified in FDA labeling

  • Requires a titration step before settling into a maintenance dose

  • Reports of fetal abnormalities with in utero exposure require caution in pregnancy

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