How Long Does Flexeril Stay In The System?

Last Updated: June 16, 2020

Authored by Sharon Levy, MD, MPH

Cyclobenzaprine is an antidepressant drug when taken relieves muscle spasms and other musculoskeletal conditions. It will be of interest to note that cyclobenzaprine can be absorbed within a few hours of intake into different body parts and detected in urine, blood, hair, and saliva. This article focuses on how long does Flexeril stay in the urine, blood, hair, and saliva, as well as variables that can affect how long it stays in the system and how to get it out of the body faster.

Cyclobenzaprine Half-Life

Cyclobenzaprine half-life is averagely eighteen hours (18 hours) and is known to have a longer half-life than most drugs before leaving the body. For those whose systems are accommodating, it will stay longer in their body for about 8 days. Those whose body system can’t tolerate it for a long time will keep it for only 4-5 days, which is the average elimination period. How long does Flexeril last? Keep reading below!

How Long Cyclobenzaprine Stays in the Urine

Flexeril will stay in urine within 4 to 14 days after the ingestion of the drug. All these durations mentioned above are not static and may differ depending on the duration of intake and dosage.

How Long Flexeril Stays in Blood

Flexeril will stay for up to 10 days after the last intake of the drug. It starts being detectable in 3-4 hours after the oral ingestion. However, the other ways of intake (sniffing or smoking) can affect the speed of metabolizing the substance. It is important to know that the duration cyclobenzaprine stays in the blood is also highly dependent on the patient or the dosage taken. Many people ask this question Is Flexeril a narcotic? Well, it isn’t.

How Long Cyclobenzaprine Stays in the Hair

Although most patients will eliminate Flexeril from their bodies within 72 hours, it is doesn’t necessary applies to hair. The traces of Flexeril can be found in hair within the 90 days after the intake in some rare cases, however, it will also depend on the hair length and other personal factors. In any way, the hair test rarely applies for cyclobenzaprine testing.

How Long Flexeril Stays in Saliva

mouth swab saliva drug testBeing part of the body system, Flexeril can stay in saliva for 3 to 10 days depending on the rate of body excretion. A prominent variable that affects the duration of Flexeril in the system is a hepatic/renal function of an individual. Patients with the hepatic disorder tend to experience a reduction of CYP450 isoenzyme function, hence, a prolongation of metabolites excretion, thereby causing an increased duration of cyclobenzaprine in the body.

Does Flexeril Show Up on a 12-Panel Drug Test?

Flexeril won’t be detected on a 12-panel drug test. Flexeril isn’t visible on regular blood, saliva, or urine test. Instead, it can be detected as an antidepressant drug in the body, and only shows up if a specific test is carried out for that. In cases like this, the patient is subjected to a special toxicology test, and only then, would cyclobenzaprine show up as an antidepressant.

Variables That Affect How Long Flexeril Stays in System

How long does Flexeril stay in system? Variables such as age/sex, body mass, metabolic rate, genetic, dosage, the frequency of drug administration among others affect how long cyclobenzaprine stays in the system. Listed below are other factors that affect how long Flexeril stays in the body.

Individual differences

Oftentimes, two people may take a drug, but one will retain it longer in the body than the other. The question is why this experience? It is simply because of some individual peculiarities regarding age/sex, body mass, metabolic rate and so on.  Cyclobenzaprine mechanism of action is to increase brainstem-mediated noradrenergic inhibition of spinal cord neurons.

The frequency/duration of drug administration

This is another variable aside individual differences that can lead to how long does Flexeril stay in the system. It can be expected to stay longer in the system of anyone who takes it at a higher frequency. For instance, this can either be taken 3 times/ day or once/day. It will stay longer in the body of the person that takes it 3 times daily than the one that takes it for just once daily.  There are some important side effects of cyclobenzaprine to look out for before taking this drug.

Drug dosage

The generally prescribed dosage is Flexeril 5mg, but sometimes doctors prescribe a higher dosage of 10mg for higher complications. The higher the dosage, the longer it takes generic Flexeril to be eliminated from the system after completion.

Other combined drugs

Either ignorant or according to doctor’s prescription, some drugs can be combined with cyclobenzaprine depending on the state of health of the individual involved. However, the combined drug tends to reduce the speed of this drug excretion. Some of these combined drugs that can hinder easy removal are chloramphenicol, Ritonavir, etc.  Flexeril and Ibuprofen.  are another drug interactions to know about.

How to Remove Flexeril From System Faster?

There are different methods of removing Flexeril from the body. They include:

  • Hydrationdoctor and patient discussing a detox plan
  • Calcium-D-Glucarate
  • CYP450 inducers drugs
  • Activated Charcoal
  • Medical Detox

Cyclobenzaprine drug test can be carried out to determine the degree of concentration in the blood. At rehab centers, people are helped through proper monitoring to get the Cyclobenzaprine off their system faster. Variables like individual differences, frequency/duration of the drug, and other combined drugs are known to affect how long cyclobenzaprine stays in the system. Medical detox can also be prescribed as the fastest on how to flush Flexeril out of the system.

Page Sources

  1. Tatiane Maria de Lima Souza Brioschi, Simone Grigoleto Schramm, Eunice Kazue Kano, Eunice Emiko Mori Koono, Ting Hui Ching, Cristina Helena dos Reis Serra, Valentina Porta, Pharmacokinetics and Bioequivalence Evaluation of Cyclobenzaprine Tablets,

Published on: November 30th, 2018

Updated on: June 16th, 2020

About Author

Sharon Levy, MD, MPH

After successful graduation from Boston University, MA, Sharon gained a Master’s degree in Public Health. Since then, Sharon devoted herself entirely to the medical niche. Sharon Levy is also a certified addiction recovery coach.


Leave a comment

  • Jackie Kreuzer
    I took 1 Flexeril 10 days ago. Will it show up on a urine drug screen
  • Kecia
    I took flexeril 10mg 6 days ago will it show up in urine test?
  • Big girl
    I am morbidly obese at 6′ 370 – always eating. Craving food. Until I started taking flexeril for an injury. I think I could lose weight if prescribed for this reason. Not craving sweets, bread, salty stuff.