Methocarbamol, sold under the brand name Robaxin among others is a medication used for short-term musculoskeletal pain.[2][3] It may be used together with rest and pain medication.[2] It is less preferred in low back pain.[2] It is not useful for cerebral palsy.[2] Effects generally begin within half an hour.[2] It is taken by mouth or injection into a vein.[2]

Common side effect include sleepiness and dizziness.[2] Serious side effects may include anaphylaxis, confusion, liver problems, and seizures.[3] Use is not recommended in pregnancy and breastfeeding.[3] Methocarbamol is a centrally acting muscle relaxant.[3] How it works is unclear, but it does not appear to affect muscles directly.[2]

Methocarbamol was approved for medical use in the United States in 1957.[2] It is available as a generic medication.[3][2] A month supply in the UK costs the NHS about £12.72 as of 2019.[3] In the US the wholesale cost of this quantity is about US$6.50.[4] In 2016 it was the 187th most prescribed medication in the United States with more than 3 million prescriptions.[5]

1 Side-effects
1.1 Abuse potential
2 Metabolism
3 Marketing
4 See also
5 References
Potential side-effects include: drowsiness, dizziness, clumsiness (ataxia), upset stomach, flushing, blurred vision, and fever. Both tachycardia (fast heart rate) and bradycardia (slow heart rate) have been reported;[6][7] these can be serious. Other serious side-effects include the development of a severe skin rash or itching, fainting, jaundice, persistent nausea/vomiting, stomach/abdominal pain, mental/mood changes, trouble urinating, and signs of infection. If taken in large amounts at once or more than directed or as prescribed, dysphoria or suicidal thoughts may occur.[8] Methocarbamol may cause urine to turn black, blue or green but the effect is harmless.[9]

Methocarbamol has a high therapeutic index, i.e., a wide range of safe and effective dosages. Consumer (OTC) doses are in the range 3–6 g per day,[10] while clinical doses can be as high as 24 g per day for severe conditions such as tetanus.[11]

Because of the potential for side-effects, this drug is considered to be a high-risk medication for the elderly.[12]