How Long Does Methocarbamol Stay in Your System? Dosage and Effects

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What Is Methocarbamol? Uses, Effects, Risks, Addiction

Methocarbamol is a prescription drug approved by the FDA in 1957, and it remains widely used today. In 2019 alone, there had been almost five million prescriptions in the US. Because of its prominence as a form of medication, it’s helpful to understand what it is, what its effects are, and the possible risks it carries.

How Long Does Methocarbamol Stay in Your System?

Every drug has a half-life, which is the time it takes for the body to expel half of the substance ingested. Each medication varies in its half-life—some medications last just a couple of hours while others stay in the blood for several days.

When our body processes methocarbamol, we generate metabolites that our bodies expel at different rates. In most cases, the half-life of methocarbamol ranges from one to two hours. We get rid of its metabolites via urination, but we only pass trace amounts of the active substance itself.

Many factors affect the time in which the drug remains in our systems, such as our age, kidney health, and the condition of our liver. Older people or those with compromised kidneys and liver tend to eliminate the substance much more slowly than younger and healthy individuals.

Will Methocarbamol Appear on a Drug Test?

Prescription medications, such as methocarbamol, sometimes result in false positives when a person gets tested for illegal drugs. The test may detect its presence and falsely flag the person as positive for the use of illicit substances. Because of this, it’s best to be aware of how long it takes Robaxin to become undetectable in examinations.

How long methocarbamol remains detectable in the body depends on which samples the laboratory will use. For example, it can remain visible in blood samples for up to 24 hours. After this period, technicians will not be likely to detect the substance in the blood.

Robaxin tends to remain active in urine samples for a more extended period than blood, and labs typically can detect the substance four days after the patient last used it. Meanwhile, hair samples make the drug visible for the longest amount of time, as it will remain active in hair for upwards of 90 days.

What Is Methocarbamol, and What Are Its Uses?

Methocarbamol is popular in the market under the brand name Robaxin or Robaxin-750, but it may also come in its generic name. This prescription medication is a muscle relaxer typically used to treat muscle spasms, especially when they occur due to skeletal muscle conditions like strains, sprains, or other injuries. It’s particularly beneficial in combination with rest and physical therapy. 

The drug typically comes in the form of oral tablets, but injectable solutions also exist. You can cut or crush these tablets, and you can take them with or without food. Not every pharmacy will have this drug, so calling ahead to check their stocks is ideal.

Methocarbamol injections can only be administered by a licensed professional. This form of the drug may help treat lockjaw, an excruciating tightening of the jaw muscles that prevents the mouth from opening. 

Methocarbamol can also treat painful muscle spasms related to tetanus. It may be used in conjunction with other forms of tetanus treatments, such as supportive care, debridement, penicillin, antitoxin, maintaining fluid balance, and tracheotomy.

Robaxin belongs to a class of medications called muscle relaxers. It works by slowing the activity of the central nervous system and blocking pain signals from reaching the brain. It doesn’t affect the skeletal muscles directly, but it relieves muscle spasms and pain by interacting with nerve endings.

Methocarbamol Dosage and Administration

Robaxin often comes in tablets containing 500 or 750 mg of the substance. In the treatment of muscle spasms and pain, adults often have to take 1500 mg (three 500-mg or two 750-mg tablets) four times a day for the first 48 to 72 hours. In severe cases, doctors may prescribe the patients to take a total of 8000 mg per day.

After the 48–72-hour period, the dosage should be decreased to approximately 4000–4500 mg. The maintenance dose would be 1000 mg four times a day for those who take the 500-mg tablet. However, for those who have the 750-mg ones, they may take 750 mg every four hours or 1500 mg three times a day.

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Methocarbamol Injection

If you miss a dose, take it as soon as you remember. However, do not consume it if you remember just a few hours before your next dose. Never attempt to take two doses at once because this could lead to severe side effects.

When it comes to injections, the relief of moderate symptoms typically takes only 1 g of methocarbamol taken intravenously or intramuscularly, then the patient will switch to oral medication. 

For those who experience severe symptoms or postoperative conditions, healthcare professionals may administer 1 g every eight hours for a maximum of three days. Patients may receive intravenous or intramuscular injections again after drug-free intervals of 48 hours if necessary.

What Are the Side Effects of Methocarbamol?

Methocarbamol is generally safe across a variety of doses, but it does have some well-known side effects. Most commonly, patients report dizziness, lightheadedness, blurred vision, nausea, headache, drowsiness, and flushed skin. They may also experience problems with their heart rate, digestive functions, and memory.

Robaxin has sedative properties, and drinking alcohol may enhance its effects. Loss of coordination is also a typical side effect of this substance, so it may not be advisable to drive or operate heavy machinery when you take this drug.

The drug may cause urine to turn a blue, green, or black color. This side effect may appear worrisome, but it’s typically harmless.

Are There Serious Risks to Taking Robaxin?

Some people are more sensitive to methocarbamol and may exhibit serious side effects that warrant emergency healthcare services. Itching, hives, swelling, a tightened sensation in the chest, and difficulty breathing are symptoms of an allergic reaction, which may be fatal if left unaddressed.

Memory loss, yellowing skin and eyes, and low white blood cell counts signal jaundice. Edema may also occur, in which the tissues swell up and the heart rate slows abnormally. Sometimes, patients who take large quantities of the substance experience suicidal ideation.

If any of these serious side effects happen, call 911 right away.

Who Cannot Take Methocarbamol?

Extra caution should be taken for patients with liver or kidney disease because the body may not be able to process and expel the substance normally. Doctors may advise you to take the drug in lower doses or prescribe a different medication schedule.

There hasn’t been sufficient data on the effects of methocarbamol in developing fetuses. Because of this, it’s best to consult your doctor if you’re pregnant or are planning to become pregnant. Breastfeeding mothers should also not take this medication because the substance can travel into breast milk and become ingested by the child, causing harmful effects. 

Is Methocarbamol Addictive?

Addiction to Robaxin is possible but rarely documented. Patients with a history of substance abuse disorders are more likely to misuse methocarbamol, but similar medications like meprobamate are more likely to induce addictive behaviors.

Seek Help with Your Addiction

Methocarbamol is one of the most commonly prescribed medications in the US, typically for the management of muscle conditions and tetanus. It comes in either a tablet or injectable form. Although the drug is generally safe, caution should be taken with pregnant or breastfeeding women or patients with liver or kidney problems. Addiction to the substance is rare, but it is possible.