Flexerilcyclobenzaprine
According to the FDA label: Cyclobenzaprine hydrochloride tablets USP are indicated as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions. Improvement is manifested by relief of muscle spasm and its associated signs and symptoms, namely, pain, tenderness, limitation of motion, and restriction in activities of daily living.
48,453 adverse event reports submitted to the FDA (2003–2026)
Top Reported Adverse Events
The most frequently reported events in association with Flexeril in the FAERS database. These are events reported by patients taking this medication, not necessarily caused by it. A single report may include multiple events.
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Pain 4,970 reports
A general report of physical discomfort, used when no more specific location is given.
Full definition in the glossary →Fatigue 3,905 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Drug Ineffective 3,511 reports
A report that the medication did not work as expected for the person taking it. This is a reporting category, not a sign the drug is defective. It simply means someone felt it was not helping their condition.
Full definition in the glossary →Nausea 3,399 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Headache 3,385 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →Off Label Use 2,849 reports
Using a medication for a condition or in a way that the FDA has not officially approved. This is common and often legal, and a report of it does not mean something went wrong. Doctors sometimes prescribe drugs off label based on their judgment.
Full definition in the glossary →Chronic Kidney Disease 2,750 reports
A long-term, gradual loss of kidney function over months or years.
Full definition in the glossary →Diarrhoea 2,521 reports
Loose or watery bowel movements, often frequent. Also spelled diarrhea in American English.
Full definition in the glossary → See all drugs reporting this event →Fall 2,383 reports
A report that the person fell down. Falls are tracked because they can signal issues like dizziness, weakness, or balance problems.
Full definition in the glossary →Arthralgia 2,382 reports
Toxicity to Various Agents 2,329 reports
A broad reporting category used when the body has a harmful response, sometimes involving more than one substance.
Full definition in the glossary →Dyspnoea 2,150 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Constipation 2,119 reports
Difficulty passing stool, or having fewer bowel movements than usual.
Full definition in the glossary → See all drugs reporting this event →Back Pain 2,086 reports
Completed Suicide 1,995 reports
A report that a person died by suicide. This is recorded in adverse event data when it occurs during medication use, and its presence does not establish that the drug was the cause. If you or someone you know is struggling, the 988 Suicide and Crisis Lifeline (call or text 988 in the US) is available 24 hours a day.
Full definition in the glossary →
Ranked by frequency of reports, not severity. The most-reported event is not necessarily the most dangerous or the most common in patients taking this drug.
Who Is Reporting
Demographics of patients in FAERS reports that included this information. Not all reports include patient demographics.
By Sex
View reporter sex data as a table
| Sex | Reports |
|---|---|
| Female | 32,219 |
| Male | 12,460 |
| Unknown | 45 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 451 |
| 18-34 | 3,008 |
| 35-49 | 7,434 |
| 50-64 | 12,515 |
| 65-74 | 5,107 |
| 75+ | 2,617 |
This shows who filed reports, reflecting who takes this drug and who tends to report, not who is at greatest risk.
Reported Outcomes
Outcomes recorded in FAERS reports that included Flexeril. A single report may involve multiple reactions, each with a different outcome. These categories are defined by FDA reporting guidelines, not by PillSignal.
View outcome data as a table
| Outcome | Reports |
|---|---|
| Other Serious | 22,884 |
| Non-Serious | 15,147 |
| Hospitalization | 13,633 |
| Death | 7,040 |
| Life-Threatening | 1,482 |
| Disability | 1,386 |
Serious outcomes are far more likely to be reported than mild ones, so this overstates how often outcomes are serious. A recorded death does not mean the drug caused it.
Report Volume Over Time
Number of FAERS reports received per quarter for Flexeril. Changes in volume may reflect shifts in prescribing rates, media attention, or reporting behavior, not changes in the medication's safety profile.
View report trend as a table
| Year | Reports |
|---|---|
| 2003 | 1 |
| 2004 | 193 |
| 2005 | 170 |
| 2006 | 138 |
| 2007 | 31 |
| 2008 | 81 |
| 2009 | 362 |
| 2010 | 729 |
| 2011 | 909 |
| 2012 | 1,279 |
| 2013 | 1,419 |
| 2014 | 1,524 |
| 2015 | 2,586 |
| 2016 | 3,265 |
| 2017 | 2,974 |
| 2018 | 3,871 |
| 2019 | 4,893 |
| 2020 | 4,395 |
| 2021 | 3,687 |
| 2022 | 3,764 |
| 2023 | 3,659 |
| 2024 | 3,664 |
| 2025 | 3,988 |
| 2026 (partial) | 871 |
The steep increase around 2004 reflects the FDA's move to electronic submission, not a change in this drug's safety. Trends track reporting volume, not risk.
Medications commonly reported with Flexeril
In FDA adverse event reports that mention Flexeril, these medications appeared most often in the same report.
- Gabapentin (12,243 reports)
- Omeprazole (10,082 reports)
- Acetaminophen (9,377 reports)
- Ergocalciferol (9,181 reports)
- Albuterol (7,195 reports)
This reflects co-occurrence in submitted reports, not evidence of drug interaction or combined risk. People often report several medications taken for the same condition or for unrelated reasons. Talk to a doctor or pharmacist about your specific medications.
Related Drugs
Other medications with similar adverse event profiles in FDA FAERS reports.
Data Source
This data is sourced from the FDA's Adverse Event Monitoring System (AEMS), formerly FAERS, via the OpenFDA API. PillSignal is not affiliated with the FDA.
View this data on the FDA website →Data last updated: June 2026