What is Cyclobenzaprine?
Cyclobenzaprine is a prescription muscle relaxant used to relieve skeletal muscle spasms and associated pain from acute, painful musculoskeletal conditions [1.2.2, 1.7.2]. Commonly known by brand names like Flexeril, Amrix, and Fexmid, it is typically prescribed for short-term use, often for two to three weeks, in conjunction with rest and physical therapy [1.3.2, 1.6.3].
Structurally related to tricyclic antidepressants, cyclobenzaprine works primarily within the central nervous system (CNS) at the brain stem level [1.7.1, 1.7.2]. It reduces tonic somatic motor activity, which helps to decrease muscle hyperactivity without interfering with overall muscle function [1.7.2]. This mechanism effectively blocks pain signals sent from the muscles to the brain, providing relief [1.4.2].
Is Cyclobenzaprine a Controlled Substance? The Official Answer
According to the U.S. Drug Enforcement Administration (DEA), cyclobenzaprine is not a controlled substance under the federal Controlled Substances Act (CSA) [1.2.1, 1.3.4]. This means it is not placed into one of the five schedules that categorize drugs based on their abuse potential and accepted medical use [1.3.1].
The reason for its non-controlled status is its relatively low risk for addiction and abuse compared to other substances like opioids or benzodiazepines [1.4.2, 1.4.4]. It doesn't activate the brain's reward centers in the same way that classic drugs of abuse do [1.4.1]. However, this does not mean the drug is without risks or potential for misuse.
Why is There Confusion? Potential for Misuse
Despite its non-controlled status, cyclobenzaprine has a known potential for misuse. Its CNS depressant effects can cause sedation, relaxation, and sometimes a feeling of euphoria, which can be sought by recreational users [1.2.2, 1.2.5]. The DEA acknowledges anecdotal reports of individuals taking cyclobenzaprine, sometimes in combination with other drugs like alcohol or benzodiazepines, to enhance these psychoactive effects [1.2.1, 1.3.1]. In 2011, there were over 11,000 emergency department visits related to the misuse of cyclobenzaprine [1.5.4].
The misuse may have seen an increase after carisoprodol (Soma), another muscle relaxant, was classified as a Schedule IV controlled substance in 2011, making cyclobenzaprine comparatively easier to obtain [1.3.1, 1.5.3]. Because of this potential for misuse, while not federally scheduled, some states may monitor its prescription through Prescription Drug Monitoring Programs (PDMPs) and may have specific regulations regarding its dispensing [1.3.2, 1.10.1].
Cyclobenzaprine vs. Other Muscle Relaxants: A Comparison
To understand cyclobenzaprine's status, it's helpful to compare it to another muscle relaxant, carisoprodol (Soma), which is a controlled substance.
| Feature | Cyclobenzaprine (Flexeril) | Carisoprodol (Soma) |
|---|---|---|
| DEA Schedule | Not a controlled substance [1.6.1] | Schedule IV controlled substance [1.6.1] |
| Abuse Potential | Lower, but potential for misuse exists, often with other CNS depressants [1.4.3] | Higher potential for misuse and dependence [1.6.1] |
| Mechanism | Acts on the brain stem to reduce muscle hyperactivity [1.7.2] | Changes nerve activity in the central nervous system [1.6.2] |
| Primary Use | Short-term relief of muscle spasms from acute painful conditions [1.9.4] | Short-term relief of muscle pain and discomfort [1.6.2] |
| Common Side Effects | Drowsiness, dry mouth, dizziness [1.9.4] | Drowsiness, dizziness, headache [1.6.2] |
Side Effects and Important Safety Information
Even when used as prescribed, cyclobenzaprine can cause a range of side effects. The most common include:
- Drowsiness [1.9.4]
- Dry mouth [1.9.4]
- Dizziness [1.9.4]
- Fatigue [1.9.4]
- Headache [1.9.4]
- Constipation [1.8.2]
Drug Interactions
Cyclobenzaprine can have dangerous interactions with other substances:
- CNS Depressants: Combining it with alcohol, barbiturates, benzodiazepines, or opioids can lead to extreme sedation, impaired coordination, slowed breathing, and potentially coma or death [1.9.1, 1.9.2, 1.9.3].
- MAO Inhibitors: Taking cyclobenzaprine with or within 14 days of using a monoamine oxidase inhibitor (MAOI) is contraindicated and can cause life-threatening reactions, including high fever and seizures [1.9.1, 1.9.2].
- Serotonergic Drugs: When taken with other drugs that increase serotonin levels (like SSRIs, SNRIs, and tramadol), there is a risk of developing serotonin syndrome, a potentially fatal condition with symptoms like agitation, hallucinations, rapid heart rate, and fever [1.9.1, 1.9.2].
Long-Term Use Risks
Cyclobenzaprine is intended for short-term use (2-3 weeks) [1.4.2]. Prolonged use is not recommended and can lead to tolerance, physical dependence, and withdrawal symptoms upon cessation, such as nausea, headache, and malaise [1.4.4, 1.8.1]. Long-term use may also increase the risk for cognitive impairment and liver damage [1.8.1, 1.8.3].
Conclusion
In summary, is cyclobenzaprine a controlled substance? No, it is not federally classified as a controlled substance by the DEA [1.2.1]. However, its status as a prescription-only medication reflects its potential for causing significant side effects and its known potential for misuse and abuse [1.2.2]. Its sedative properties, especially when combined with other CNS depressants, create serious health risks [1.9.1]. Patients should only use cyclobenzaprine under the strict guidance of a healthcare provider, adhere to the prescribed dosage and duration, and be fully aware of the potential drug interactions.
For more detailed information from a primary source, you can review the DEA's drug fact sheet on Cyclobenzaprine.
