Cyclobenzaprine (sold under the brand name Flexeril, among others) is a medication used for muscle spasms from musculoskeletal conditions of sudden onset. It is not useful in cerebral palsy. It is taken by mouth. Use is not recommended for more than a few weeks.Common side effects include headache, feeling tired, dizziness, and dry mouth. Serious side effects may include an irregular heartbeat. There is no evidence of harm in pregnancy, but it has not been well studied in this population. It should not be used with an MAO inhibitor. How it works is unclear.Cyclobenzaprine was approved for medical use in the United States in 1977. It is available as a generic medication. In 2020, it was the 39th most commonly prescribed medication in the United States, with more than 16 million prescriptions. It was not available in the United Kingdom as of 2012. Medical use
Cyclobenzaprine is used, in conjunction with physical therapy, to treat muscle spasms that occur because of acute musculoskeletal conditions. After sustaining an injury, muscle spasms to stabilize the affected body part occur, which may increase pain to prevent further damage. Cyclobenzaprine is used to treat such muscle spasms associated with acute, painful musculoskeletal conditions. It decreases pain in the first two weeks, peaking in the first few days, but has no proven benefit after two weeks. Since no benefit is proven beyond that, therapy should not be continued long-term. It is the best-studied muscle relaxer.
However, nonbenzodiazepine (including cyclobenzaprine) treatment was found to have a lower risk of medication abuse and continuation of use against medical advice. Side effects such as sedation and ataxia are also less pronounced with nonbenzodiazepine antispasmodics.In a study on the treatment of musculoskeletal pain treatment with cyclobenzaprine alone or in combination with ibuprofen, no significant differences in pain scores were noted among the three treatment groups. Peak benefit was found to occur on day seven of the treatment for all groups. Formulations
By mouth, cyclobenzaprine is marketed as Apo-Cyclobenzaprin, Fexmid, Flexeril and Novo-Cycloprine. It is available in generic form. A once-a-day, extended-release formulation, Amrix, is available. Cyclobenzaprine is also used by compounding pharmacies in topical creams. References
External links

"Cyclobenzaprine". Drug Information Portal. U.S. National Library of Medicine.