Starting Dose of Flexeril (Cyclobenzaprine)
The recommended starting dose of cyclobenzaprine (Flexeril) is 5 mg three times daily, which can be increased to 10 mg three times daily based on individual patient response. 1
Standard Dosing Regimen
- Start with 5 mg three times daily for most patients, as this represents the FDA-approved initial dose that balances efficacy with tolerability 1
- The dose may be increased to 10 mg three times daily after assessing initial response and tolerability, typically within the first few days of treatment 1
- Treatment duration should be limited to 2-3 weeks, as cyclobenzaprine is indicated only for acute musculoskeletal conditions and prolonged use is not recommended 1
Evidence Supporting Lower Starting Doses
The 5 mg three times daily starting dose is supported by robust clinical trial data showing:
- The 5 mg dose is as effective as 10 mg three times daily for relief of muscle spasm, local pain, and improved range of motion 2
- Lower incidence of sedation with 5 mg compared to 10 mg (the most common adverse effect), making it better tolerated while maintaining therapeutic benefit 2
- Onset of relief occurs within 3-4 doses of the 5 mg regimen, demonstrating rapid therapeutic action 2
- Treatment efficacy is greatest in the first 4 days, with declining benefit after the first week, supporting short-term use 3
Special Population Considerations
- Elderly patients should receive less frequent dosing due to increased risk of adverse effects, though specific dose reductions are not defined in the FDA label 1
- Hepatically impaired patients require less frequent dosing to avoid drug accumulation 1
- The 2.5 mg three times daily dose was not significantly more effective than placebo in clinical trials and should not be used 2
Clinical Pearls and Pitfalls
- Avoid the common error of starting at 10 mg three times daily in all patients, as this increases sedation risk without additional benefit for most individuals 2
- Drowsiness is dose-related and the most common adverse effect, occurring alongside dry mouth; starting at 5 mg minimizes this while maintaining efficacy 2, 3
- Efficacy is independent of sedation, as demonstrated by subanalysis showing meaningful treatment effects in patients who did not report somnolence 2
- Combination with NSAIDs like ibuprofen does not provide additional benefit over cyclobenzaprine monotherapy for acute neck or back pain with muscle spasm 4