Methocarbamol Side Effects And The Dangers Of Overdose

Last Updated: May 2, 2024

Ahmed Zayed, MD Authored by Dr. Ahmed Zayed
0 sources cited

Robaxin, the brand name of Methocarbamol, is a muscle relaxant that is used to treat skeletal issues and pain associated with injury, arthritis, and other bone and muscle conditions. It is in a class of drugs called muscle relaxers. These drugs work by utilizing different mechanisms to relax stiff muscles thereby easing pain and discomfort. Methocarbamol effects are not severe, in some cases, and they can disappear quickly.

However, some people might experience some effects, which should be examined by a doctor, especially if it is a sign of an overdose or allergy to methocarbamol. Read along to find out the common, rare, and severe aftereffects of the medicine, check methocarbamol warnings during pregnancy and breastfeeding, the dangers of overdose, and how it can be used safely.

Common Side Effects Of Robaxin

Robaxin drug class is a muscle relaxant, and it works by acting on the central nervous system blocking pain messages being sent to the brain. It can be combined with rest and physical therapy in the treatment of pain or injury. The blocking action of this medicine causes some common, as well as, severe, and rare aftereffects similar to the use of other muscle relaxants. The most common effects of the medicine do not require a physician’s attention as they would vanish on their own. Studies indicate that Methocarbamol is very efficient in patients but produces only minor psychomotor and cognitive impairments.

Some of the Common and Less Serious Methocarbamol Effects Are Listed Below:


  • Skin rashes
  • Flushed feeling
  • Heartburn


  • Rhinitis


  • Nausea
  • Vomiting
  • Upset stomach
  • Constipation
  • Indigestion


  • Headaches
  • Drowsiness
  • Insomnia
  • Loss of balance or coordination
  • Confusion
  • Memory problems
  • Spinning sensation
  • Dizziness

This Methocarbamol 500mg side effect list is inconclusive as such report any notable changes both cognitive, gastrointestinal, or physical, for early treatment. Ignoring these aftereffects can lead to serious health problems. Remember to seek more information before administering the drug to avoid future health consequences.

Robaxin Side Effects

Severe Side Effects Of Robaxin

Apart from the common unpleasant effects, some patients might experience severe methocarbamol side effects. These effects could require the urgent attention of a medical professional.

Get Emergency Help if Any or More of the Following Severe Side Effects Occur:


  • Chest pain or discomfort
  • Fever or chills
  • Dark urine
  • Slower or faster than normal heart rate
  • Difficulty in swallowing
  • Hives especially swelling on the face, eyes, lips, and tongue
  • Numbness of face, hands, and/or feet
  • Loss of bladder control
  • Ulcers in the mouth
  • Yellow skin and eyes indicating jaundice
  • Unusual bleeding or bruising
  • Joint or muscle pain


  • Black or clay-colored stool
  • Loss of appetite
  • Stomach pain
  • Bloody or black vomit


  • Memory problems
  • Seizures

The medicine may cause other effects such as lightheadedness and itching. Always remember to report any physical, gastrointestinal or cognitive changes to a physician for prompt action. Also, remember to take the medicine as prescribed and follow the information on the box or leaflet on how to take the medication.

Rare Methocarbamol Side Effects And Possible Complications Of Long-Term Use

Like any other medicine, long-term use and overdose of methocarbamol can be dangerous to health and, in some cases, can be fatal. That is why long-term intake is not advisable or abuse is discouraged. The following medical conditions are rare side effects of Methocarbamol and should be reported immediately if they are spotted.

  • Thrombophlebitis – when a blood clot obstructs the free flow of blood in one of the veins in the legs.
  • Low blood pressure
  • Low levels of white blood cells
  • Fainting
  • Build up of bilirubin causing Jaundice
  • Anaphylaxis (a life-threatening allergic reaction)
  • Dyskinesia (involuntary erratic movements of the face, arms, or legs)
  • Tonic-Clonic Seizure (convulsions)
  • Memory loss
  • Insomnia

Studies indicate that methocarbamol has not been linked to kidney or liver diseases as such it is unlikely it will affect the two organs. There may be other side effects of Methocarbamol that are not listed. Be sure to take this medication under a doctor’s supervision to forestall any serious health problems. Also, remember to heed the methocarbamol warnings listed in the information on the box or the leaflet inside the packaging.

A woman holds a bottle of pills in the pharmacy.

Methocarbamol Warnings And Contraindications

Robaxin can have adverse effects on health so it is best to seek medical advice before administration. This medication can weaken the ability to think clearly or react. So, it is advisable to avoid any work that requires a lot of thinking or driving. People who are allergic to methocarbamol are advised to stay off this medicine. Patients need to strictly follow the methocarbamol warnings on the box or leaflet to avoid health complications.

Other Factors Also Need to Be Considered Before Deciding Whether or Not to Use Robaxin. These Factors Are Described Below:

  • Age – The safety and efficacy of methocarbamol for children below the age of 16 have not been established. There are not enough studies that can determine the effect of Robaxin on children, thereby making it a decision of the doctor to determine if its administration to children will outweigh the presumptive side effects. Similarly, there are not enough studies to show whether the use of Robaxin in elderly patients will be affected because of their old age.
  • Gender – Robaxin should be used with caution by women who are trying to conceive. Also, taking Robaxin during the early stages of pregnancy is strongly discouraged. However, the medical doctor will decide whether the pros of taking the drug far outweigh the cons.
  • Drug InteractionsRobaxin interactions with other drugs should also be considered before starting its use. Some of these drug interactions might even be fatal. According to the study about the interaction of methocarbamol with ethanol, it was presented that this interaction can lead to combined central nervous system depression and eventually death. A doctor needs to know all the medications that a patient is using to determine if they can be used with Robaxin. Doctors may adjust the Robaxin dosage to avoid its interactions with the other drugs.
  • Diseases And Discomforting Health Conditions – Some diseases may aggravate methocarbamol 500 mg side effects, or the diseases may get aggravated because of methocarbamol. A kidney or liver disease might increase the side effects of methocarbamol because of its slower expulsion from the body. Some diseases like myasthenia gravis may worsen because of Robaxin. A medical doctor would determine whether a patient should take this medication or avoid it. The physician would weigh the merits against the demerits of administering the drug. If it turns out Robaxin would have minimal impact on the health of the patient compared to advantages, then the use of the drug will be encouraged.
A woman on sofa reads about Methocarbamol side effects.

Robaxin Warnings In Pregnancy And Breastfeeding

Robaxin is a pregnancy Category C medicine, which means that there are not enough studies about the effects and side effects of the drug in pregnant women. It is not known whether the drug will harm an unborn baby. Thus its use is usually avoided in pregnancy unless considered by the doctor to be necessary. The effects of Robaxin and breastfeeding have also not been established, and there is not enough research in this regard. According to this publication about the drug details of Robaxin, it is stated that methocarbamol is excreted in the milk of dogs. However, there is not enough research to show whether this is the case in humans also. Thus, caution should be exercised when using methocarbamol during breastfeeding.

Robaxin Overdose

Though there are no concrete studies on the overdose of the medicine, reports indicate that using the drug alongside alcohol and other CNS depressants may result in overdose. It is important to stay off alcohol and CNS depressants while administering the drug to avoid negative consequences. In terms of the drug’s toxicity, limited information is available. However, two adults were known to deliberately administer 22-30 mg and 30-50 mg of Robaxin without serious toxicity. The only symptom exhibited was dizziness. However, there have also been cases of fatal overdose.

Signs And Symptoms Of Robaxin Overdose

There are several signs and symptoms that a user who overdoses on the medication would exhibit. Some of these symptoms may not require any medical treatment and may vanish on their own.

Here Is a List of Some Signs and Symptoms of Robaxin Overdose to Look Out For:

  • Seizures
  • Shaking of one side of the body
  • Sweating
  • Severe dizziness
  • Severe drowsiness
  • Loss of consciousness

Taking an overdose of the drug can lead to death in some cases. Therefore, it is advised that users strictly follow the directions of the physician or the instructions on the packaging. If a user takes too much of the medicine, the best solution is to consult a medical center for assistance.

Safe Use Of Robaxin

Robaxin, like all muscle relaxants, tends to have some common and rare side effects. However, in cases of pain associated with injury and skeletal issues, its use and benefits outweigh its side effects. It is considered a better choice as compared to some other muscle relaxants. For example, considering Methocarbamol vs Flexeril, Flexeril cannot be taken for more than 2 to 3 weeks. If Flexeril is stopped abruptly, it can cause withdrawal symptoms in the patient. Methocarbamol has much fewer withdrawal symptoms.

To Minimize the Risks and Side Effects of Methocarbamol, and to Ensure the Safe Use of Methocarbamol, There Are Certain Cautions Which One Can Exercise. These Are Discussed Below:

  • Patients should take Robaxin on an empty or full stomach, as prescribed by the doctor.
  • Patients should not exceed the dosage prescribed by the doctor.
  • Patients should not use Robaxin for a longer period than as prescribed by the doctor.
  • Patients should discuss all the drugs they are taking as well as their other medical conditions or diseases with the doctor before he prescribes Robaxin.
  • Patients should not consume alcohol with methocarbamol. Alcohol and some drugs can interact with the drug and cause unpleasant side effects.

Also, patients should remember that Robaxin abuse can happen, and this condition should be treated as fast as possible because of its dangerous consequences. Rehabilitation centers can offer a broad range of services to overcome this addiction effectively.

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Page Sources

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Published on: January 29th, 2020

Updated on: May 2nd, 2024


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