Is methocarbamol (Robaxin) addictive: abuse, side effects, and withdrawal

Methocarbamol abuse is the misuse of the muscle relaxant medication, often sold under the brand name Robaxin. Methocarbamol is a central nervous system depressant with sedative and musculoskeletal relaxant properties. While methocarbamol itself is not considered a highly abused substance, inappropriate or excessive consumption, as well as concomitant use with other substances often leads to certain health risks.

The side effects of methocarbamol abuse are drowsiness and sedation, dizziness and lightheadedness, confusion, impaired cognitive function, seizure, balance, and motor impairment. Additionally, individuals abusing methocarbamol experience urine discoloration, upset stomach, nausea or vomiting, jaundice, headaches, blurred vision, muscle weakness, and respiratory depression as adverse effects of the drug.

The withdrawal of methocarbamol abuse refers to the range of symptoms that occur when a person who has been using methocarbamol, particularly in high doses or over a prolonged period, abruptly stops or significantly reduces their usage. Withdrawal symptoms like nausea, headaches, rebound muscle spasms or pain, insomnia, and others arise because the body becomes accustomed to the presence of the medication. When the medication is discontinued, the body needs time to adjust to its absence, which leads to physical and psychological symptoms.

Is Methocarbamol (Robaxin) addictive?

Yes, methocarbamol (Robaxin) is addictive if misused or abused, however, the likelihood of developing addiction to this medication is relatively low if used as prescribed under the guidance of a healthcare professional.

Methocarbamol is not classified as a controlled substance by the US Drug Enforcement Administration (DEA). While methocarbamol has a low potential for abuse and addiction, there are certain risks and concerns associated with its use, especially among individuals with a history of substance use disorders.

A 1989 study by Preston KL. et al, titled “Evaluation of the abuse potential of methocarbamol,” investigated the subjective and behavioral effects of methocarbamol, lorazepam, and placebo in adult males with histories of recreational substance abuse. Lorazepam demonstrated the highest potential for abuse among the studied drugs. Nevertheless, the research indicated that individuals using methocarbamol also exhibited signs of addiction when the drug dosage was elevated, particularly in individuals with sedative abuse histories.

Caution is advised when using methocarbamol in individuals concurrently taking substances with abuse potential, including alcohol and medications for sleep disorders.

Are muscle relaxants addictive?

Yes, muscle relaxants are addictive, but the degree of risk is influenced by factors such as the specific muscle relaxant prescribed, the patient’s medical history, and individual susceptibility.

While muscle relaxants primarily target the central nervous system (CNS) to alleviate muscle spasms and tension, their mechanisms of action often lead to sedation and drowsiness. Certain muscle relaxants, such as carisoprodol, cyclobenzaprine, metaxalone, and diazepam have a higher risk of abuse or dependence because they suppress brain activity, causing sedation and reducing the sensation of pain.

As per the Drug Enforcement Administration report on “CARISOPRODOL (Trade Name: Soma®)” from December 2019, the subjective effects of carisoprodol resemble other CNS depressants like meprobamate, pentobarbital, and chlordiazepoxide, and demonstrate rewarding effects, indicating a potential for abuse. Extended misuse of carisoprodol at elevated doses often results in the development of tolerance, dependence, and withdrawal symptoms.

As stated in StatPearls’ article on “Diazepam,” last updated in August 2023, diazepam is a Schedule IV controlled substance due to its potential for abuse. The likelihood of developing dependence and tolerance increases especially in individuals prone to addiction, when subjected to extended treatment or high doses.

The study mentions that medical professionals should exercise careful consideration when prescribing methocarbamol to older patients, who are at risk of polypharmacy, and those with a history of addiction, to minimize the risks of developing dependence or experiencing adverse effects.

What is Methocarbamol abuse?

Methocarbamol abuse is the non-medical and inappropriate use of the medication for purposes other than its intended medical use.

Methocarbamol is a muscle relaxant prescribed to alleviate muscle spasms and musculoskeletal pain. Methocarbamol belongs to the class of skeletal muscle relaxants, acting in the spinal cord or brain to suppress overstimulated nerve pathways, as stated in the StatPearls article on “Methocarbamol,” last updated in November 2022, 

The specific way methocarbamol operates in the human body has not been definitively determined, still, it is suggested to involve a general depression of the CNS, as stated by the DailyMed’s drug label information on “METHOCARBAMOL tablet, coated,” updated in September 2020. 

This mechanism results in the blocking of pain sensations by preventing nerve impulses from reaching the brain. In essence, the drug helps alleviate muscle pain by reducing the transmission of pain signals, leading to a decrease in the perception of discomfort.

Methocarbamol possesses abuse potential and often leads to complications when taken concurrently with other substances with abuse potential, such as alcohol, benzodiazepines, opioids, and CNS depressants, as outlined in the Drugs.com article on “Methocarbamol,” last revised in August 2023.

The clinical application of methocarbamol is commonly restricted to the management of acute musculoskeletal pain. However, methocarbamol is frequently prescribed off-label for various painful conditions such as acute and chronic non-specific low-back pain, inflammatory arthritides, fibromyalgia, and abdominal muscle cramps in individuals with cirrhosis, as highlighted in the StatPearl’s article on “Methocarbamol,” last updated in November 2022.

At elevated doses, methocarbamol’s likelihood of being abused is heightened, especially in those who have a history of sedative or hypnotic abuse, and its misuse leads to sensations akin to a “high” due to side effects like drowsiness and dizziness.According to Daniel J. Mazanec and Russell C. DeMicco’s 2017 book “Benzel’s Spine Surgery, 2-Volume Set (Fourth edition),” chapter “Medical Management of Neck and Low Back Pain,” around half of individuals undergoing muscle relaxant treatment encounter unwanted effects, with the most frequent being dizziness and sedation. Considering these traits, it has a comparatively low likelihood of being abused.

How common is Methocarbamol abuse?

Methocarbamol abuse is common, considering the broader trends related to the usage of muscle relaxants, highlighted by a threefold increase observed between 2005 and 2016, as per 2005 study from Penn Medicine, titled “Long-term Use of Muscle Relaxants Has Skyrocketed Since 2005”. 

During this period, although the number of new muscle relaxant prescriptions, including methocarbamol, remained relatively stable, around 6 million per year, office visits for ongoing muscle relaxant drug therapy surged from 8.5 million in 2005 to 24.7 million in 2016. Notably, older adults, constituting 22.2% of all muscle relaxant visits in 2016, surpassed their representation in the US population, which stood at 14.5%.

While the use of skeletal muscle relaxants is less frequent compared to other substances like pain relievers, it remains a significant worry in the US. In 2011, around 53,000 visits to the emergency department were attributed to the misuse or abuse of muscle relaxants, with 18% of these instances involving simultaneous alcohol consumption, according to Witenko C. et al. 2014 study, titled “Considerations for the appropriate use of skeletal muscle relaxants for the management of acute low back pain”.

Moreover, the study revealed that 44.5% of individuals used muscle relaxants for more than one year, even though each medication in this category is typically recommended only for short-term use and has not been thoroughly studied for prolonged management.

What are the signs of Methocarbamol abuse?

The signs of methocarbamol abuse are listed below.

• Sedation or drowsiness: Individuals abusing methocarbamol often exhibit signs of unexplained sedation or drowsiness, characterized by an unusual and excessive tendency to sleep or lethargy that goes beyond the expected therapeutic effects.
• Increased dosage without medical guidance: A potential indicator of methocarbamol abuse is the unauthorized increase in dosage, where individuals take higher amounts of the medication than prescribed by a healthcare professional, seeking heightened effects or sensations.
• Doctor shopping: Those engaged in methocarbamol abuse attempt to obtain the medication from multiple healthcare providers or sources, a behavior known as “doctor shopping” that raises concerns about non-medical use.
• Using methocarbamol without a prescription: Abuse often manifests in the consumption of methocarbamol without a valid prescription, indicating an unauthorized and potentially risky use of the medication for non-medical purposes.
• Combining with other substances: Individuals misusing methocarbamol engage in the concurrent use of the medication with other substances, such as alcohol or other drugs, potentially intensifying the sedative effects and posing additional health risks.
• Cravings for methocarbamol: Cravings for methocarbamol manifest as a strong and persistent desire to consume the medication, often exceeding prescribed doses. Individuals experiencing cravings exhibit increased preoccupation with obtaining and using methocarbamol, despite potential negative consequences.
• Continued use despite negative consequences: A concerning sign of methocarbamol abuse is the persistent use of the drug. This persistence occurs despite experiencing adverse consequences on health, relationships, or daily functioning. It reflects a potential disregard for the negative impact of substance misuse.

What are the side effects of Methocarbamol abuse?

The side effects of methocarbamol abuse are listed below.

• Drowsiness and sedation: Abusing methocarbamol results in heightened drowsiness and sedation, surpassing the expected therapeutic effects. Excessive sleepiness and a state of calmness occur, impacting daily functioning and potentially leading to dangerous situations.
• Dizziness and lightheadedness: Methocarbamol abuse induces sensations of dizziness and lightheadedness, affecting balance and increasing the risk of falls or accidents. Individuals misusing the drug experience difficulties in maintaining stability and coordination.
• Confusion: Methocarbamol abuse results in a state of confusion, where individuals experience disorientation and difficulty in understanding or processing information. This side effect contributes to cognitive disturbances and compromises daily activities.
• Impaired cognitive function: Improper use of methocarbamol impairs cognitive functions such as memory, attention, and decision-making. Users encounter difficulties in mental tasks, impacting overall cognitive performance.
• Seizure: As per StatPearls’ article on “Methocarbamol,” last updated in November 2022, there have been documented instances of seizures in individuals with a history of epilepsy following methocarbamol administration intravenously, along with reported cases of polysubstance toxicity.
• Balance and motor impairment: According to a 2004 study by Charles Dillon et al., titled “Skeletal Muscle Relaxant Use in the United States,” there is apprehension that the central sedative effects of methocarbamol compromise balance and the safe operation of vehicles and machinery. Older individuals are especially vulnerable to these side effects of the drug.
• Urine discoloration: Methocarbamol abuse manifests in urine discoloration, where individuals notice the black, blue, or green color of their urine, as mentioned in the MedlinePlus article on “Methocarbamol,” last updated in August 2017. This side effect is an indication of the body processing and eliminating the medication.
• Upset stomach: Unregulated use of the drug disrupts normal gastrointestinal function, contributing to abdominal discomfort, digestive issues, nausea, or changes in bowel habits.
• Nausea or vomiting: Abusing methocarbamol leads to nausea or vomiting, causing discomfort and negatively impacting an individual’s overall well-being.
• Jaundice: In cases of methocarbamol abuse, individuals experience jaundice, a condition marked by the yellowing of the skin or eyes. This indicates liver dysfunction or damage, emphasizing the importance of monitoring for such signs during improper use.
• Headaches: Headaches are a side effect of methocarbamol abuse, contributing to persistent or severe pain. This can further contribute to the overall discomfort experienced by individuals who misuse the drug.
• Blurred vision: Methocarbamol abuse causes blurred vision, impacting visual perception and clarity. This side effect interferes with daily activities and increases the risk of accidents or injuries.
• Respiratory depression: In extreme cases of methocarbamol abuse, respiratory depression often occurs, involving slowed or shallow breathing. This serious condition is life-threatening and requires immediate medical attention.

Does Methocarbamol cause serotonin syndrome?

Yes, methocarbamol causes serotonin syndrome as a side effect, although its occurrence is very scarce and was identified in only 0.08% of cases among 15,323 individuals, according to the research from eHealthMe, titled “Methocarbamol and Serotonin syndrome – a phase IV clinical study of FDA data” and published in November 2023.

The study highlighted that this side effect was especially observed in females aged 60 and above, particularly among those who had Narcolepsy, had been using Remeron and methocarbamol for 2 to 5 years.

Leslie V. Simon and Michael Keenaghan defined serotonin syndrome (SS) as a potentially fatal condition triggered by the consumption of serotonergic medications in their article “Serotonin Syndrome,” published in StatPearls and updated in July 2023.

As described in the 2016 study “Treating Depression with the Mephenesin Analog Skeletal Muscle Relaxant Methocarbamol,” published in the Scientific Research, there is a potential interference in clinical urine tests for carcinoid tumors or pheochromocytoma due to the oral intake of methocarbamol.

This interference is attributed to the increased excretion of 5-hydroxyindoleacetic acid (5-HIAA) and vanillylmandelic acid (VMA) in urine following methocarbamol ingestion, leading to false positives in drug level measurements.

Additionally, the study suggests that the oral intake of methocarbamol elevates levels of serotonin and catecholamine-like substances in the head, potentially impacting biochemical markers used in clinical testing. Methocarbamol intake appears to influence serotonin and catecholamine-like substances in the cranium, as suggested by structural formulas.

It is crucial to exercise caution when using methocarbamol in conjunction with other medications that increase serotonin levels.

Can you overdose on Methocarbamol?

Yes, you can overdose on methocarbamol if the recommended dosage is exceeded or if it is taken in combination with other substances that affect the central nervous system. 

According to the findings of Lebby TI. et al.’s 1990 study, titled “Skeletal muscle relaxant ingestion,” the risks of morbidity and death are minimal when individuals consume skeletal muscle relaxants alone. However, the likelihood of adverse outcomes rises when multiple substances are ingested.

Moreover, the study revealed that methocarbamol overdose cases were not common, and they typically do not present a significant threat to life unless there is exposure to multiple drugs at the same time.

In more recent data from DailyMed’s drug label information on “METHOCARBAMOL tablet, coated,” updated in September 2020, it is outlined that methocarbamol overdose often occurs when combined with alcohol or other CNS depressants, leading to symptoms such as nausea, drowsiness, blurred vision, hypotension, seizures, and coma.

Additionally, fatalities have been documented in the cases of this drug overdose in isolation or combined with other CNS depressants, alcohol, or psychotropic drugs.

A 1990 study “A fatal interaction of methocarbamol and ethanol in an accidental poisoning,” published in the Journal of Forensic Sciences, analyzed a case of acute alcohol intoxication combined with methocarbamol usage, which resulted in a fatal outcome.

The fatal drug interaction resulted from the simultaneous ingestion of methocarbamol and ethanol. Combining these substances is contraindicated due to the synergistic sedative-hypnotic properties they possess.

As stated by the US Food and Drug Administration (FDA) in the report  “FDA warns about serious risks and death when combining opioid pain or cough medicines with benzodiazepines; requires its strongest warning” from August 2008, the increasing concurrent use of opioid medications with benzodiazepines or other CNS depressants, including skeletal muscle relaxants, has led to severe side effects, like respiratory depression and fatalities.

Therefore, the FDA urges against consuming alcohol with these medications, as alcohol depresses the CNS and heightens the risk of severe sedation, respiratory depression, coma, and death.

What are the symptoms of Methocarbamol withdrawal?

Methocarbamol is not typically known to cause withdrawal symptoms, nevertheless, it induces a sense of euphoria or high in the user, which prompts them to crave the drug upon its discontinuation. Methocarbamol withdrawal symptoms vary in intensity and duration depending on the individual, the duration of use, and the dosage.

The symptoms of methocarbamol withdrawal are listed below.

• Nausea: Individuals experiencing methocarbamol withdrawal often encounter persistent nausea, characterized by an uncomfortable sensation of wanting to vomit. This symptom can contribute to an overall feeling of discomfort and unease during the withdrawal process.
• Headache: Methocarbamol withdrawal may be accompanied by persistent and intense headaches, causing throbbing or aching sensations. This symptom significantly impacts an individual’s daily activities and contributes to an overall sense of discomfort and distress during the withdrawal period.
• Rebound muscle spasms or pain: Stopping methocarbamol abruptly leads to the recurrence of the original symptoms it was prescribed to treat. This return of symptoms happens suddenly and is potentially more intense.
• Drowsiness: Drowsiness is characterized by an overwhelming and persistent feeling of sleepiness or lethargy. This symptom hinders normal daily functioning and contributes to a sense of fatigue and sluggishness during the substance withdrawal process.
• Dizziness: Individuals undergoing methocarbamol withdrawal experience pronounced dizziness, characterized by a spinning or lightheaded sensation. This symptom leads to difficulties with balance and contributes to an increased risk of falls and accidents during the withdrawal process.
• Vomiting: Methocarbamol withdrawal involves vomiting, which leads to dehydration, nutritional imbalances, and an overall sense of physical discomfort during the withdrawal period.
• Insomnia: Individuals undergoing methocarbamol withdrawal experience insomnia, characterized by difficulties falling asleep or staying asleep. This symptom leads to fatigue, irritability, and disruptions in the sleep-wake cycle during the withdrawal process.
• Anxiety: Methocarbamol withdrawal is sometimes accompanied by heightened anxiety, characterized by feelings of unease, apprehension, and restlessness.
• Mood fluctuations: Withdrawal from methocarbamol is characterized by mood fluctuations, involving changes in emotional states such as irritability, sadness, or mood swings. These variations impact an individual’s overall well-being and interpersonal relationships during withdrawal.

What are the treatments for Methocarbamol abuse?

The treatments for methocarbamol abuse are listed below.

• Detoxification: If the individual is physically dependent on methocarbamol, a supervised detoxification process is necessary. This involves gradually reducing the dosage under medical supervision to manage withdrawal symptoms.
• Counseling and behavioral therapy: Counseling and behavioral therapy are beneficial for addressing the psychological aspects of methocarbamol abuse. Cognitive-behavioral therapy (CBT)  helps individuals learn the coping skills needed for long-term recovery.
• Support groups: Participation in support groups or 12-step programs provides a sense of community and support. Groups such as Narcotics Anonymous are helpful for individuals dealing with substance abuse issues.
• Inpatient or outpatient rehabilitation: Depending on the severity of methocarbamol abuse, individuals often undergo treatment in an inpatient rehabilitation facility or attend outpatient programs. Inpatient programs offer 24-hour care, while outpatient programs provide flexibility for those with milder cases.
• Individualized treatment plans: Treatment plans are typically tailored to the individual’s unique needs, considering factors such as co-occurring mental health issues, social support, and readiness for change.
• Aftercare treatment: Aftercare treatment for methocarbamol abuse refers to the ongoing support and interventions provided to individuals who have completed an initial phase of treatment for methocarbamol misuse or addiction. This phase of care is designed to help individuals maintain their recovery and prevent relapse.