How long does flexeril stay in your system?

by Admin on October 8, 2009

I took a flexeril for pain like a week ago, i have to give blood on october 5, will that show up?

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Justin E October 8, 2009 at 5:02 pm: Yes, Flexeril will show up in a drug screening.

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, so it would take 3.75 days for it to clear out of your body completely.

Keep in mind that half-life can vary from patient to patient, so this is not a hard and fast rule. Half-life is also affected if the patient has altered kidney or liver function.