Response and effectiveness

The time to peak cyclobenzaprine concentration varies depending on the formulation used (around 7 hours for the extended-release form). Some effects may be noticed in as little as 20 to 30 minutes. Immediate-release tablets have a half-life of four to six hours. Extended-release tablets have a 24-hour duration of action.

5mg of cyclobenzaprine is said to be as effective as 10mg, but with fewer side effects.

For muscle spasms caused by brain injury or disease, cyclobenzaprine is ineffective.