How Long Do Muscle Relaxers Last In Your Body?

Muscle relaxers are multipurpose medications for the treatment of muscle pain and spasms ranging from muscle strains and sprains to cerebral palsy and multiple sclerosis.

While these medications are very effective for their purpose, you can still experience muscle relaxers side effects in the process. If you were prescribed a muscle relaxant, knowing how long these medications last in your body can help you manage dosages, avoid potentially harmful drug interactions and ensure compliance with drug screening tests, if necessary.

Continue reading to learn about muscle relaxers benefits and their duration to understand their impact on your body.

Table Of Contents:

• Muscle Relaxers Mechanism of Action in the Body
• How Long Do Muscle Relaxers Stay In Your System?
• Muscle Relaxers and Drug Testing
• Muscle Relaxers Side Effects
• How Long Does Muscle Relaxer Stay in Your System − Bottom Line
• People Also Ask

Muscle Relaxers Mechanism of Action in the Body

Muscle relaxers, or muscle relaxants, are a diverse group of prescription medications designed to reduce muscle tension and pain induced by muscle spasms. They achieve this through various mechanisms of action, which can be generally classified into two types: 1) antispasmodics and 2) antispastics.

Antispasmodics are primarily used to treat muscle spasms. Muscle spasms are sudden, involuntary contractions of a muscle or group of muscles and can be caused by injuries to tendons, ligaments or muscles. For example, if you strain or sprain your lower back, you might experience muscle spasms. Examples include:

• Cyclobenzaprine (Flexeril)
• Methocarbamol (Robaxin)
• Carisoprodol (Soma)

Antispastics are used to treat muscle spasticity. Muscle spasticity involves continuous muscle tightness or stiffness, which can interfere with movement and speech. This condition is often seen in individuals with neurological disorders such as multiple sclerosis, cerebral palsy or spinal cord injury. Examples include:

• Baclofen (Lioresal)
• Tizanidine (Zanaflex)
• Dantrolene (Dantrium)

How Long Do Muscle Relaxers Stay In Your System?

Considering the broad spectrum of muscle relaxers’ uses, patients need to be aware of the amount of time these medications stay active in the human body. However, factors influence this duration. For example, children may have a shorter half-life of drugs compared to adults.

Factors affecting muscle relaxant duration in the body include:

• Dosage: Higher doses will naturally take longer to eliminate from your body.
• Individual factors: Kidney Function, liver function and metabolism impact the body’s drug metabolism.
• Form of administration: An oral tablet or capsule takes longer to be absorbed than liquid forms.
• Gender:  Liver enzymes metabolize medication differently in men and women.

Half-life of Muscle Relaxers

Another important factor is the medication’s half-life. To better understand how a muscle relaxer stays in your system, it’s helpful to consider muscle relaxers half-life and the age group the patient belongs to.

A muscle relaxer half-life is the time it takes for the drug’s concentration in the bloodstream to be reduced by half. This measure determines how long a drug’s effects will last, how often it needs to be administered and how long it might be detectable in the body.

Let’s review the average half-life of the different muscle relaxers you can find in the market:

Let’s say you are wondering: how long does methocarbamol stay in your system?

The complete elimination of a drug from the body can be estimated using its half-life. Typically, it takes about 4 to 5 half-lives for a drug to be eliminated from the system. The formula to calculate the time for complete elimination is:

Complete Elimination Time=Half-Life × 5

Let’s apply this formula to methocarbamol, which has a half-life of approximately 1 to 2 hours.

• For the lower end (1 hour):

Complete elimination time = 1 hour × 5 = 5 hours

• For the upper end (2 hours):

Complete elimination time = 2 hours × 5 = 10 hours

So, methocarbamol would be expected to be eliminated from the body in approximately 5 to 10 hours. You can apply this formula to other muscle relaxants you are taking. However, take into account that patients with renal or hepatic impairment are likely to have a prolonged half-life. Proceed with caution in these cases.

Muscle Relaxers and Drug Testing

If you’re preparing to start a new job, you might be concerned: Do muscle relaxers show up in a drug test?

Despite their potential for addiction, muscle relaxers are usually not detectable or are specifically tested during routine drug screenings; you will want to know before important urine or blood tests.

Check the below to know how long muscle relaxers stay in the body and remain detectable in blood, urine, and saliva samples.

Muscle Relaxers Side Effects

Even with a small dose of a muscle relaxer, there are important potential risks to be aware of. While these medications effectively treat various symptoms, high doses can lead to side effects.

The most common side effects associated with muscle relaxers include:

• Drowsiness
• Dizziness
• Fatigue
• Weakness
• Dry mouth
• Headache
• Nausea
• Constipation

Remember that these medications are intended for short-term use only. Experts generally recommend limiting the use of these drugs to a maximum of three weeks because they have not proven effective for muscle spasms beyond that duration.

If you experience serious side effects like rash, itching/swelling, dark urine, irregular heartbeat, chest pain, severe stomach pain or difficulty breathing, stop the medication and seek medical attention as soon as possible.

How Long Does Muscle Relaxer Stay in Your System − Bottom Line

Muscle relaxers are commonly prescribed for muscle spasms or tightness. While they are generally safe when taken as directed, knowing about their metabolism in the body ensures you avoid taking another dose. At the same time, a significant amount of the drug remains in your body, preventing potential side effects and interactions.

Each muscle relaxer has unique characteristics that affect how long it stays in your body. Use the drug’s complete elimination formula to practice safe medication treatment. Muscle relaxers like diazepam and carisoprodol are controlled drugs, and you can become dependent on them. When prescribed a muscle relaxer, use it responsibly and follow your healthcare provider’s instructions.

People Also Ask

How long does a muscle relaxer last?

The effects of a muscle relaxer typically last between 4 to 24 hours, depending on the specific medication and dosage.

How long does it take for muscle relaxers to get out of your system?

Muscle relaxers can take 1 to 10 days to fully clear from your system, depending on the muscle relaxant, dosage and individual metabolism.

Do soma and Flexeril show up the same on a drug test?

No, Soma and Flexeril have different chemical structures and may be detected differently on drug tests, depending on the specific test used.

Page Sources

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