Flexeril will take between 3 and 4 days to be removed from your system. Before that time, it will definitely show up in a urine test. How long a drug stays in your blood and/or urine is usually determined by its half-life. The half-life of a drug is the time it takes your body to metabolize and excrete the medication, so that half of it is removed from your body. Generally speaking, it takes five half-lives to fully eliminate a drug from your blood or urine. Flexeril has a half-life of 18 hours. The drug stays active for about 5 half-lives. Therefore, the time to metabolise will be 5 times 18 hours. So it will take 90 hours before nearly all of it is out of your system. This equates to 3.75 days for it to clear out of your body completely. This half-life time can vary from person to person, and will depend on how much of a dosage was ingested, and both the person’s weight and metabolism. Flexeril is the 5 mg and 10 mg tablet form of cyclobenzaprine, a drug used as a muscle relaxant. It works by blocking nerve impulses (or pain sensations) that are sent to your brain. Flexeril is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.
