Flexeril Elimination Half-Life: How Long Does It Stay in Your System?

The elimination half-life of flexeril (cyclobenzaprine) is approximately 1.5 hours. This means that it takes about 1.5 hours for the concentration of flexeril in the body to decrease by 50%. It takes about 5 half-lives, or 7.5 hours, for flexeril to be eliminated from the body. However, flexeril may be detectable in the urine for up to 4 days.