What is the smallest dose, timing, and duration of Cyclobenzaprine (Flexeril) therapy?

From the Guidelines

Cyclobenzaprine should be prescribed at a starting dose of 5 mg three times daily, with a maximum duration of 2-3 weeks, due to its efficacy in short-term pain relief and potential for increased side effects with extended use, as supported by the most recent and highest quality studies 1.

Key Considerations

• The medication should be taken at regular intervals throughout the day, with many patients finding benefit in taking one dose approximately 30-60 minutes before bedtime to help with sleep due to its sedative properties.
• Cyclobenzaprine works as a muscle relaxant by acting on the central nervous system to reduce muscle hyperactivity without affecting muscle strength.
• Common side effects include drowsiness, dry mouth, and dizziness, so it's advisable to avoid driving or operating machinery until you know how the medication affects you.
• If 5 mg is not effective, your healthcare provider may increase the dose to 10 mg, but higher doses generally increase side effects without significantly improving efficacy.

Evidence Summary

The evidence from multiple systematic reviews and trials, including those published in the Annals of Internal Medicine 1, suggests that cyclobenzaprine is effective for short-term pain relief in acute low back pain, but its efficacy for chronic low back pain is less clear. The majority of trials had a duration of 2 weeks or less, with limited evidence supporting longer use.

Important Notes

• Skeletal muscle relaxants, including cyclobenzaprine, were associated with a higher total number of adverse events and central nervous system adverse events compared with placebo, although most events were self-limited and serious complications were rare 1.
• It's essential to take cyclobenzaprine exactly as prescribed and not to abruptly stop the medication if you've been taking it regularly.

From the FDA Drug Label

Cyclobenzaprine hydrochloride tablets should be used only for short periods (up to two or three weeks) The smallest dose is not specified in the label.

• Dose and Timing: Not directly stated in the label.
• Duration: Up to two or three weeks 2

From the Research

Cyclobenzaprine Dosage and Administration

• The smallest dose and timing of cyclobenzaprine are not explicitly stated in the provided studies 3, 4, 5, 6.
• However, it is mentioned that cyclobenzaprine is effective in treating musculoskeletal conditions, including acute low back pain and muscle spasm 3, 4.

Duration of Treatment

• The duration of cyclobenzaprine treatment is not specified in the studies, but it is noted that combination therapy with cyclobenzaprine and naproxen was used for 14 days in a randomized, open-label trial 4.
• The study found that combination therapy was associated with less objective muscle spasm and tenderness, and greater motion of the lumbosacral spine, compared to naproxen alone 4.

Safety and Efficacy

• Cyclobenzaprine has been evaluated in the most clinical trials and has consistently been found to be effective in treating musculoskeletal conditions 3.
• However, there is limited data on the relative efficacy and safety of cyclobenzaprine compared to other muscle relaxants, such as baclofen and tizanidine 3, 6.
• A study found that baclofen was associated with a higher risk of injury and delirium compared to tizanidine in older adults with musculoskeletal pain 6.