How Long Do Muscle Relaxers Stay In The System And Show Up On Tests?

Last Updated: June 10, 2020

Authored by Olivier George, Ph.D.

Muscle relaxant drugs are commonly prescribed to people who report symptoms that may include spasms, cramps, and similar events. Studies have shown that muscle relaxants are prescribed to approximately 18.5% of patients with back pain problems, with COX-2 inhibitors and NSAIDs also being common prescription options. Many people want to know whether muscle relaxers show up on drug test and how long the chemicals in these medicines would remain in their systems.

Half-Life Of Muscle Relaxers

Whether using muscle relaxers medication to treat back pain or muscle-related pain symptoms affecting a different part of the body, many patients do want to know how long does it takes for muscle relaxers to wear off. One useful way of providing an overview of the time that a drug will remain active in the body is to consider its half-life.

 nurse checking time
There is a number of different options that people can use when they suffer from muscle-related symptoms. It is possible to choose an OTC muscle relaxant or rather opt for a prescription one instead, depending on the severity of the pain. Since there are different types of these medicines on the market, it is essential to take note of the fact that the half-life of each may differ.
Check the names of prescription muscle relaxers, along with the average half-life of each:

Drug Name Half-Life
Meprobamate 10 hours (Chronic use: up to 48 hours)
Cyclobenzaprine Eight hours to 36 hours (Average: 18 hours)
Vecuronium 70 minutes
Atracurium 20 minutes
Rapacuronium 10 minutes to 20 minutes
Mivacurium 10 minutes to 20 minutes
Metocurine 50 minutes

The half-life of muscle relaxers for fibromyalgia, injury, back pain, and other conditions that leads to muscle-related symptoms, helps to provide a more accurate overview of how a dosage should be calculated for a specific individual.

What Influences The Period Of Muscle Relaxers Staying In The System?

When it comes to considering how long do muscle relaxers stay in the system, it is essential to note that there is no specific time frame that can be mentioned here. While it is useful to consider the half-life of a drug, there are many other factors that ultimately have an impact on how long the chemicals will remain in the system of a person.

One of the main factors that will impact the period during which the muscle relaxer’s chemicals will remain in the body is the specific type of drug that was used. There is a significant variety of these medicines that a person can use – and each has its own muscle relaxant side effects, half-life period, as well as the time that the body will take to expel the chemical completely.

male doctor explaining muscle relaxers half-life
The dosage that the person takes will also have an impact. The greater the dose, the longer it takes for the body to get rid of all the chemicals that it was introduced to.
Apart from these factors, there are a couple of other factors that should also be considered when trying to determine how long a specific type of muscle relaxant would remain within the system:

  • Sex plays a role, as there is a difference in how liver enzymes process medication in men and women.
  • Age is another factor that plays a part in providing an overview of the period during which the muscle relaxant would remain in a person’s system. As the body ages, there is a reduction in kidney function, as well as liver function.
  • Weight and the percentage of body fat also plays a part. A larger person may require a higher dose for the drug to work effectively.
  • The general well-being of a person also plays a role. A person with existing conditions that affect their kidneys, as well as their liver, may have impaired functionality in terms of how drugs are metabolized.
  • Drinking on muscle relaxers is also known to be responsible for prolonged staying in the system.

Muscle Relaxers On Drug Tests

The common question is, will muscle relaxers show up on a drug test? Understanding how certain long drugs stay in the system is important. While this may not be such a big concern with all-natural muscle relaxers, it is important to consider these factors when using a pharmaceutical product.
Despite the fact that muscle relaxers can get one high, they are not specifically tested. Some people still want to know how long the medication will remain in their system and for how long they will test positive for specific chemicals.
Below is a guide that provides further details of different muscle relaxants, as well as the time they generally stay in the body and remains detectable.

Drug Name Blood Test Urine Sample Saliva Sample
Baclofen 72 hours for regular doses 48 hours (Up to 10 days with high doses) 48 to 72 hours
Flexeril Up to 10 days 4 to 4 days 3 to 10 days
Soma 24 hours 2-3 days, Variable (Chronic / Acute) up to 4 hours

Flushing Muscle Relaxers Out Faster

Even though several suggestions have been made that certain claim drugs can be flushed out of the system faster, it should be noted that these drugs have a specific half-life and their elimination will be affected by a number of factors related to the medication, as well as the patient being treated.

Doctor talking to her male senior patient

Still, there are a few tips that might be worth a try. Hydrating the body thoroughly with about three liters of water per day could be a good way to speed up the elimination process of the chemicals that are in the body. Some have also suggested that cranberry juice, in addition to the water, can be helpful to clear out the chemicals faster. Exercise is yet another potential option that may be utilized. Furthermore, avoiding foods that could slow down metabolism is also an important step to take when trying to eliminate these drugs from the body at an accelerated rate.
When the use of muscle relaxers do become a problem, a person might require a professional detoxification procedure to get rid of the chemicals in their system. Professional addiction treatment can be provided to the person. This would usually include a program in a drug rehab that assists in reducing withdrawal symptoms, while also enabling the person to stop their habit of potentially abusing these muscle relaxants.

Page Sources

  1. Luo X, Pietrobon R, Curtis LH, Hey LA, Prescription of nonsteroidal anti-inflammatory drugs and muscle relaxants for back pain in the United States.,
  2. Corey Witenko, Robin Moorman-Li, Carol Motycka, Kevin Duane, Juan Hincapie-Castillo, Paul Leonard, Christopher Valaer, Considerations for the Appropriate Use of Skeletal Muscle Relaxants for the Management Of Acute Low Back Pain,

Published on: August 14th, 2019

Updated on: June 10th, 2020

About Author

Olivier George, Ph.D.

Olivier George is a medical writer and head manager of the rehab center in California. He spends a lot of time in collecting and analyzing the traditional approaches for substance abuse treatment and assessing their efficiency.


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