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
Robaxin
Flexeril vs. Robaxin Dosage
Flexeril
Robaxin
| 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 |
| 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
| 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
| 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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