Methocarbamol: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on July 13, 2023.

1. How it works

• Methocarbamol is a muscle relaxant that may be used in addition to other treatments for the relief of discomfort associated with acute, painful musculoskeletal conditions.
• Experts are not sure how methocarbamol works because it has no direct effect on muscle; however, its effects may be due to its sedative properties or the way it blocks nerve impulses to the brain.
• Methocarbamol belongs to the class of medicines known as muscle relaxants.

2. Upsides

• May be used as a muscle relaxant in addition to rest and physical therapy to relieve discomfort associated with acute, painful, musculoskeletal conditions (third-line therapy for the relief of chronic back pain).
• May be used for the relief of tetanus spasms.
• Available as an injection.
• Generic methocarbamol is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Drowsiness, flushing, low blood pressure, dizziness on standing, seizures, rash, blurred vision, and a metallic taste in the mouth. Rarely, has been associated with life-threatening allergic reactions. May also cause a headache, fever, slow heartbeat, dyspepsia, nausea or vomiting, confusion, nystagmus, blurred vision, and other adverse effects.
• The sedation caused by methocarbamol may affect a person's ability to drive or operate machinery. Alcohol should be avoided.
• Not suitable for people with a previous allergic reaction to methocarbamol.
• This may increase the risk of falls; seniors may be more at risk.
• May interact with several other medicines including those that cause sedation (including opioids, benzodiazepines, and sedating antihistamines).
• Safety and effectiveness in children younger than 16 years has not been established.
• May cause color interference in certain screening tests for 5-hydroxyindolecetic acid (5-HIAA) using nitrosonaphthol reagent and in screening tests for urinary vanillylmandelic acid using the Gitlow method.
• Has been associated with fetal and congenital abnormalities when given to pregnant women so methocarbamol should not be used during pregnancy, particularly early pregnancy. Women taking methocarbamol should not breastfeed their babies unless the benefits outweigh the risks.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Methocarbamol is only given when other treatments for musculoskeletal pain have not worked. Its main side effect is drowsiness and it should not be used in children or seniors.

5. Tips

• May be taken with or without food.
• Do not drink alcohol while taking this medicine.
• Do not drive, operate machinery, or engage in hazardous tasks while taking methocarbamol.
• Methocarbamol may make you more likely to fall over. Remove any trip hazards around your home, such as loose rugs.
• Do not take any other medication, including medicines brought over-the-counter, in addition to methocarbamol, without checking with your doctor or pharmacist to make sure they are compatible.
• Seek urgent medical advice if you develop unexplained flu symptoms, a slow heart rate, extreme dizziness, seizures, or a yellowing of your skin or eyes.
• Store your methocarbamol tablets at room temperature, 68 to 77F (20 to 25C).

6. Response and effectiveness

• Methocarbamol starts working in about 30 minutes and its full effects are seen within 2 hours.
• Methocarbamol is relatively short-acting and needs to be taken three to four times a day as directed by a doctor.

7. Interactions

Medicines that interact with methocarbamol may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with methocarbamol. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with methocarbamol include:

• anti-anxiety medications such as lorazepam or diazepam
• anticonvulsants such as phenytoin, valproic acid
• antidepressants, such as amitriptyline, imipramine, nortriptyline, fluoxetine, or sertraline
• antihistamines that cause sedation, such as diphenhydramine
• duloxetine
• monoamine oxidase inhibitors, such as selegiline, isocarboxazid, or phenelzine (interaction may be life-threatening)
• opioid analgesics such as oxycodone and morphine
• other muscle relaxants such as cyclobenzaprine
• sleeping pills, such as zolpidem
• some chemotherapy treatments
• some medications used to treat mental illness, such as clozapine and thioridazine
• topiramate.

Alcohol may worsen the side effects of methocarbamol such as drowsiness and dizziness.

May interact with some laboratory tests.

Note that this list is not all-inclusive and includes only common medications that may interact with methocarbamol. You should refer to the prescribing information for methocarbamol for a complete list of interactions.

References

• Methocarbamol. Revised 02/2023. Pharmasource Meds, LLC https://www.drugs.com/pro/methocarbamol.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use methocarbamol only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2024 Drugs.com. Revision date: July 13, 2023.

Medical Disclaimer