How Long Does Flexeril Stay in Your System?

Flexeril is a common prescription substance used to treat a variety of muscle disorders. How long it is present in the body depends on many factors.   

How Long Does Flexeril Stay in Your System

Table of Contents

What is Flexeril?

Flexeril is the name brand for cyclobenzaprine, a muscle relaxant used to treat pain and stiffness usually in the case of muscle spasms.1 While it is often used to aid in the treatment of pain, it is not a prescription painkiller. For individuals who use this substance, many may question “how long does Flexeril stay in your system?” This article will describe the uses of Flexeril and which factors affect how long it stays in the body. 

What does Flexeril Treat?

Flexeril is used to treat a variety of muscle-related disorders. These tend to fall into two categories of pathophysiology: muscle spasms and muscle stiffness.2

Muscle spasms are uncontrollable contractions of the muscle that lead to movement. While minor spasms can be normal or may appear as a side effect of certain substances, severe or long-term muscles spasms can be dangerous. Not only do they have the potential to cause great discomfort, but they can also cause someone to accidentally inflict harm on themselves depending on the severity and range of motion of the spasm. For example, a severe muscle spasm in the arm could lead the patient to hit something nearby.

Muscle stiffness is the opposite and consists of a decreased range of motion and the inability to fully exercise and use certain muscles. It can lead to reduced activity which can cause muscle atrophy. Chronic stiffness can also cause nerve pain. 

Drug Class

While Flexeril is a muscle relaxant, it belongs to the more specific class of skeletal muscle relaxants.

There are two ways that skeletal muscle relaxants work. Some substances in this class may impact the central nervous system to muffle the excessive stimulation or nerve pathways. Others will directly impact muscle fibers, though they may cause side effects (such as drowsiness) in the central nervous system. 

Drug Schedule

Flexeril is not a scheduled drug, meaning that the United States FDA has not deemed it a controlled substance, though it can be abused due to its sedative and relaxing effects. 

Street Names

There are very few street names for Flexeril. One of the only known slang terms for this substance is “Flex-ies”. However, due to its tendency to be misspelled, different but similar spelling variations such as “flexreal” are often accepted slang names. 

Is Flexeril Addictive?

In many medical societies, Flexeril is considered non-addictive since it does not impact the brain or body the same way that other substances do. Most often, substance use disorders involving Flexeril occur when the substance is abused alongside alcohol. 

Statistics on Flexeril Use

As an uncontrolled substance, there are not many statistics available to analyze its addictiveness of this drug or rates of abuse. However, in 2011, there are statistics on the amount of Flexeril prescribed that year – specifically, over twenty-five million prescriptions. 

Common Flexeril Side Effects

Flexeril can be an efficient way to treat muscle pain, whether from an injury or a disorder. However, when taken incorrectly or abused, it does have the potential to lead to side effects.3 Side effects can range in severity depending on individual and dose and may include:

  • Drowsiness
  • Fatigue
  • Anxiety
  • Headaches
  • Dizziness
  • Nausea
  • Change in bowel patterns
  • Blurred vision
  • Dry mouth
  • Confusion
  • Acid reflux
  • Abdominal pain
  • Fever

In extreme cases, Flexeril can also cause an overdose when taken in too large amounts or when abused alongside other substances, such as alcohol. Flexeril overdose is a medical emergency and can lead to death without proper care. 

How is Flexeril Metabolized?

Any time a substance is introduced into the body, the body works to break it down and process it. How efficiently and quickly this process is performed depends on many factors, including those involving the individual as well as the substance itself. 

Flexeril Half-Life

Determining Flexeril’s half-life depends heavily on the individual qualities of the patient. However, based on previous studies, it is estimated that its half-life is anywhere from eight to thirty-six hours.4

This fact means that after this time, exactly half of the initial amount of Flexeril will still be present in the body. The other half will have been metabolized and eliminated. 

Factors That Affect Detection Time

Each body processes a substance differently, and Flexeril is included. As a result, when determining the probability that this drug is still detectable, acknowledging these factors is a significant step.

Body Fat Content

For a substance to be effective, it must be transported around the body through the blood and absorbed into the tissue. This process is especially important for certain types of muscle relaxants that interact with the muscles directly.5

However, a higher body fat content indicates a larger amount of adipose tissue, which is the tissue beneath the skin that acts as insulation. Since the substance will also need to be absorbed here, it can take longer for the entire process of absorption and elimination to occur, thus increasing the amount of time that Flexeril is detectable in the body.

Higher body fat content can also slow metabolism, which is another key factor in Flexeril detection.

Weight and Height

Weight and body fat content are not the same factors, though both play a significant role in the detection of a substance. Lower weights can maintain a higher fat content and vice versa, which is why both factors should be considered. Higher weights indicate more tissue and area for blood to travel, which can slow the rate of absorption.

If the rate of absorption is slowed, so is the rate of elimination. As a result, Flexeril may be detectable for longer in those with higher weights compared to lower ones. This aspect is the same for height, as there is more distance for blood to travel to allow the substance to fully saturate into all tissues.


As a person ages, their body responds to stimuli, including substances, differently. Body fat content and distribution can change, and metabolism can slow. These changes can cause Flexeril to be detectable for a longer amount of time.5

Metabolism Speed

As witnessed with other key factors, metabolism and the speed at which the body processes substances are some of the most significant factors in determining how long Flexeril is detectable.5

Size of the Last Dose Taken

The body is only able to process and eliminate a certain amount of a substance at a time. As a result, while smaller doses may be removed from the system, larger doses may require additional time to metabolize.

Amount of Time of Abuse

Chronic abuse is often related to higher amounts of Flexeril in the body at a single time, especially if little time passes between doses. As a result, those with Flexeril addiction may retain the substance longer.5

Liver Health

The liver is one of the most important organs in processing waste. Any time drugs such as Flexeril or even alcohol are introduced to the body, they can damage the liver, impacting its ability to function properly. Chronic abuse can decrease liver health, which reflects in its ability to metabolize and reduce the detectable period of Flexeril in the system. 

Flexeril Detection Test

Since different factors can impact how long Flexeril can last in the body, it is essential to find objective ways to determine whether the substance is present. This process is done through detection tests, which can come in many different forms. 


Urine drug tests are also known as urinalysis. These types of tests involve viewing a sample of urine for the presence of any substances such as Flexeril. They can detect the presence of this substance up to seventy-two hours from the last dose. 


Hair tests are rarely used in day-to-day detection tests. However, with the longest period of detection, they can show Flexeril use up to ninety days after the last dosage. 


Blood tests will only demonstrate use if the last Flexeril dose occurred within recent hours. 


Like blood, saliva tests will only detect the presence of a substance a few hours after the last dosage. 

Treatment for Flexeril Addiction at The PAC Program

Flexeril addiction can lead to a variety of harmful side effects that can impact one’s daily quality of life. However, addiction can be treated, helping to reduce or even undo the negative side effects that may have occurred with substance abuse. The PAC Program offers several Flexeril addiction treatment options, including these listed below.  


For many patients, detoxification, or detox, is the first step to treating addiction. Detox gives the body the time it needs to fully metabolize and eliminate all traces of the substance without any additional doses being administered.

Detox should be pursued in a medical setting under the guidance of a health professional. Not only can detox lead to a period of discomfort known as withdrawal, but it can also be dangerous if not completed correctly, such as in the case of substance tapering. 


Therapy and counseling are often used when treating substance use disorders. While formats and focus may vary between different types of therapies, all share the ability to help treat Flexeril addiction.

One of the most common therapies utilized in the treatment of addiction is cognitive-behavioral therapy (CBT). CBT helps reestablish the connection between thoughts and behaviors that may become disruptive with substance abuse.

There is also integrative treatment. In integrative treatment, various therapies may be utilized to maximize benefits. 


Medication-assisted treatment, also known by the acronym MAT, is a type of Flexeril addiction treatment, as well as a useful treatment for many other substance use disorders and addictions. MAT utilizes prescription medication and the guidance of a medical professional to boost the rates of a successful, long-term recovery.  

Inpatient Care

Inpatient care is a form of treatment involving either a long-term or short-term stay in a rehabilitation center. It provides the opportunity to immediately access medical help and undergo therapies and counseling in a safe, secure environment.

However, due to the vacuum inpatient care can create, it’s often followed by an outpatient program. 

Outpatient Care

Outpatient care provides regular access to treatment while still allowing the patient to continue with their daily life. Outpatient care can consist of many forms of treatment, including therapy and support groups. 


If you or a loved one needs help, please call us at
623-523-4748 and our team at Blueprints For Recovery in Arizona will help.

Related Content

Learn More

In-Network with Most Major Insurance Providers

Fill out our free and confidential form to see how your insurance could cover the cost of treatment. No commitment required.