Two medicines, side by side
Chlorzoxazone vs cyclobenzaprine
Chlorzoxazone and cyclobenzaprine are both labeled for muscle spasms and spasticity. Drugs@FDA records approvals of chlorzoxazone since 1958 and of cyclobenzaprine since 1977. Pharmacies paid $0.210 per chlorzoxazone 500 mg tablet and $0.0171 per cyclobenzaprine 10 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. Cyclobenzaprine's other strengths are brand-only: $29.61 per tablet (Tonmya 2.8 mg tablet sl).
Check it at the source: the chlorzoxazone FDA label on DailyMed (effective September 5, 2023); the cyclobenzaprine FDA label on DailyMed (effective February 21, 2025).
Highlights of the chlorzoxazone record
Chlorzoxazone (Parafon Forte Dsc) · label of September 5, 2023
Used for
From the label: indicationsChlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.
On the market
- Earliest approval on file
- August 15, 1958
- Generic labelers
- 19 labelers
- Pharmacy cost
- $0.210 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 2
Highlights of the cyclobenzaprine record
Cyclobenzaprine (Flexeril) · label of February 21, 2025
Used for
From the label: indicationsCyclobenzaprine 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. […]
On the market
- Earliest approval on file
- August 26, 1977
- Generic labelers
- 59 labelers
- Pharmacy cost
- $0.0171 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 5
Source: FDA drug labels via openFDA (Chlorzoxazone label of September 5, 2023, Cyclobenzaprine label of February 21, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do chlorzoxazone and cyclobenzaprine differ on the record?
Both are in FDA's class muscle relaxants.
Generics: chlorzoxazone since 1981; cyclobenzaprine since 1988 (Drugs@FDA).
| Chlorzoxazone | Cyclobenzaprine | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity | Muscle spasms and spasticity, Nerve pain and fibromyalgia |
| Pharmacologic class | Muscle Relaxant | Muscle Relaxant |
| How it works (label) | n/a | n/a |
| Half-life (label) | n/a | Cyclobenzaprine is eliminated quite slowly, with an effective half-life of 18 hours (range 8 to 37 hours; n=18); plasma clearance is 0.7 L/min. |
| Earliest approval on file (Drugs@FDA) | August 15, 1958 | August 26, 1977 |
| First generic approved | October 6, 1981 | February 29, 1988 |
| Generic labelers (NDC) | 19 labelers | 59 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.210 per tablet (Chlorzoxazone 500 mg tablet) | $0.0171 per tablet (Cyclobenzaprine 10 mg tablet) |
| 12-month price change | -5% | -10% |
| Boxed warning | No | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 2 | 5 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 1,296 | 50,442 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What do the labels say about using others of their kind?
Cyclobenzaprine label, warningsIf concomitant treatment with cyclobenzaprine hydrochloride and other serotonergic drugs is clinically warranted, careful observation is advised, particularly during treatment initiation or dose increases (see PRECAUTIONS :
Source: FDA drug labels via openFDA
What next?
- Alternatives to chlorzoxazone
- every medicine labeled for the same conditions