Methocarbamol interactions to avoid

Learn what medicines you should avoid while taking this muscle relaxant

By Stephanie Melby, Pharm.D. | Sep. 21, 2023

Methocarbamol is a generic prescription medication that is a skeletal muscle relaxant. Previously known under the brand name Robaxin, methocarbamol can be used to treat various painful musculoskeletal conditions. Some conditions methocarbamol can be used for include muscle spasms, muscle strains, muscle sprains, and muscle-related injuries. Methocarbamol is believed to relax the muscles in the body by central nervous system (CNS) depression, a process that allows the body to relax. Skeletal muscle relaxants like methocarbamol are typically used for short-term muscle pain. Typically, people will additionally perform physical therapy and increase rest to help treat their musculoskeletal pain and relieve discomfort. There are methocarbamol tablets and methocarbamol injections (given under the care of a healthcare professional) for those unable to take medication by mouth.

While methocarbamol can be an effective treatment option for some people, there are drug interactions that are important to be aware of and avoid. Medications can have dangerous drug interactions with other medications, certain foods, alcohol, and supplements. Drug interactions may make a certain drug less effective, cause unwanted side effects, or increase the action of a drug. As a medication that affects the CNS and can cause sedation, drug interactions with methocarbamol are very important to avoid, as increased sedation can put people at risk.

Key takeaways:

Methocarbamol causes sedation, and certain drug interactions can further increase the sedation effects of methocarbamol, leading to dangerous falls or accidental injuries.
Taking methocarbamol with other CNS depressants or alcohol can increase the risk of dangerous sedation, falls, and accidental injuries like bone fractures.
Some drug interactions with methocarbamol can increase the side effects of dizziness, drowsiness, confusion, blurred vision, or vertigo.
Some people must avoid activities such as driving or operating machinery due to drug interactions with methocarbamol.
Older adults (people who are older than 65 years) have a greater risk of dangerous sedation from methocarbamol drug interactions.
Healthcare providers can review a medication list, identify potential drug interactions, and make necessary adjustments to the medication list.

If a dangerous mixture of medications has been consumed, seek immediate medical help or contact Poison Control for help.

Methocarbamol–drug interactions

While various drugs can interact with methocarbamol, other CNS depressants are the primary drugs to monitor or avoid. CNS depressants can interact with methocarbamol and cause an increase in serious side effects. Other CNS depressants include barbiturates, benzodiazepines, opioids, and sleeping pills.  

Barbiturates

Barbiturates are prescription medications that are a type of sedative/hypnotic drug. These drugs can be used for various conditions, including seizure disorder, insomnia, preoperative anxiety, and anesthesia induction. Since barbiturates also depress the central nervous system (CNS), taking methocarbamol with a barbiturate can increase the risk of CNS depression. This drug interaction can lead to symptoms of ataxia (impaired coordination), confusion, drowsiness, respiratory depression, and weakness. Caution should be used when combining these medications, and the prescribing doctor should monitor therapy. If taken together, people should always be on alert for signs and symptoms of a drug interaction.

Examples of common barbiturates include:

Benzodiazepines

Benzodiazepines are prescription drugs that are another type of CNS depressant. These medications can be used for many different conditions, including anxiety disorders, insomnia, acute status epilepticus, induction of amnesia, spastic disorders, seizure disorders, and agitation. If combined with methocarbamol, there is a potential for a drug interaction leading to dangerous CNS depression. This drug interaction can lead to symptoms of impaired coordination, confusion, drowsiness, lightheadedness, respiratory depression, and weakness. Healthcare providers should use caution and monitor therapy if these drugs are prescribed or consider a dose reduction of one or both drugs. It’s important to always be on alert for signs and symptoms of a drug interaction.

Examples of common benzodiazepines include:

Opioids

Opioids are prescription medications that are analgesics (pain relievers) that also work by depressing the central nervous system. Opioids can be used to help manage pain that is typically moderate to severe. In order to avoid unnecessary use, opioid analgesics are only used for pain management if opioids are appropriate. Very dangerous drug interactions can occur if methocarbamol is taken with an opioid. This interaction could lead to excessive CNS depression, such as respiratory depression, hypotension (low blood pressure), sedation, or coma. If possible, the healthcare team should avoid this combination or consider a dose reduction of one or both drugs. It’s important for patients and caregivers to monitor for signs and symptoms of a drug interaction, such as slowed breathing, trouble breathing, or excessive sedation.

Examples of common opioids include:

Sleep Medications

While there are a variety of sleeping pills that cause drowsiness, the non-benzodiazepine sleep aids (also called z-drugs) are CNS depressants that work to slow down the nervous system. These sleep aids can be used to treat insomnia and may be used to help people fall asleep or stay awake throughout the night. Combining methocarbamol with a non-benzodiazepine can increase the risk of CNS depression. This drug interaction can lead to prolonged or excessive CNS depression. Caution should be used when combining these medications, and the prescribing doctor should monitor therapy. If taken together, the prescribing doctor should consider a dose reduction of one or both drugs. This drug interaction has also been associated with greater psychomotor impairment, next-day driving impairment, and an increased risk for complex behaviors such as “sleep-driving.”

Examples of common Z-drugs include:

Other methocarbamol interactions

Aside from medications, there are other types of methocarbamol interactions. Drinking alcoholic beverages or using cannabinoid-containing products can lead to potentially dangerous interactions with methocarbamol. 

Methocarbamol and alcohol

Like methocarbamol, alcohol is a CNS depressant that slows down the nervous system. People who drink alcoholic drinks such as beer or cocktails can often experience slurred speech, unsteady movement, disturbed perceptions, impaired motor control, and an inability to react quickly. Combining alcohol and methocarbamol adds extra nervous system depression that can cause severe sedation, an increased risk of falls, and a greater chance of accidental injury. People who drink alcohol should always check with their doctor or pharmacist if they can combine alcohol with their medications.

Methocarbamol and cannabinoid-containing products

Cannabinoid-containing products can potentially cause added CNS depressant effects if combined with methocarbamol. Several studies have shown that acute use of cannabis or tetrahydrocannabinol (THC, the primary known psychoactive component of cannabis) can enhance sedative, psychomotor, respiratory, and other adverse effects of CNS depressant drugs. To avoid potentially dangerous sedative effects, people should avoid cannabinoid-containing products and unprescribed, illicit, or recreational use of other CNS depressants.

How to minimize methocarbamol interactions

It’s important that the healthcare team is aware of all medical conditions and has a medication list, including prescription drugs, over-the-counter (OTC) medications, herbal products, and supplements. Even OTC and supplement products can have dangerous drug interactions. Pharmacists are great resources and can provide additional drug information and medical advice when picking up medication from the pharmacy.

Certain medical conditions can impact whether a drug will be safe or not for a person. Methocarbamol should be used cautiously in people with liver disease, kidney impairment, or seizure disorders. It is unknown if methocarbamol is present in breast milk, so caution is typically advised when using it in breastfeeding women. Knowing the warning signs of potential life-threatening interactions with methocarbamol is also important. Be aware of these symptoms, which include increased sedation, impaired coordination, confusion, drowsiness, lightheadedness, respiratory depression, and weakness.

When to talk to a healthcare provider about methocarbamol interactions

Even though many serious drug interactions are included above, several other potential methocarbamol drug interactions are not included. To ensure proper management and monitoring, people should communicate openly with their healthcare providers about all medications, supplements, and medical conditions. Alternative medication options may be better treatment options for some people.