Two medicines, side by side
Chlorzoxazone vs metaxalone
Chlorzoxazone and metaxalone are both labeled for muscle spasms and spasticity. Drugs@FDA records approvals of chlorzoxazone since 1958 and of metaxalone since 1962. Pharmacies paid $0.210 per chlorzoxazone 500 mg tablet and $0.452 per metaxalone 800 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like.
Check it at the source: the chlorzoxazone FDA label on DailyMed (effective September 5, 2023); the metaxalone FDA label on DailyMed (effective January 11, 2023).
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 metaxalone record
Metaxalone (Skelaxin) · label of January 11, 2023
Used for
From the label: indicationsMetaxalone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts 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. Metaxalone does not directly relax tense skeletal muscles in man.
On the market
- Earliest approval on file
- August 13, 1962
- Generic labelers
- 33 labelers
- Pharmacy cost
- $0.452 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 0
Source: FDA drug labels via openFDA (Chlorzoxazone label of September 5, 2023, Metaxalone label of January 11, 2023); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do chlorzoxazone and metaxalone differ on the record?
Both are in FDA's class muscle relaxants.
Generics: chlorzoxazone since 1981; metaxalone since 2010 (Drugs@FDA).
| Chlorzoxazone | Metaxalone | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity | Muscle spasms and spasticity |
| Pharmacologic class | Muscle Relaxant | Muscle Relaxant |
| How it works (label) | n/a | Mechanism of Action The mechanism of action of metaxalone in humans has not been established, but may be due to general central nervous system (CNS) depression. |
| Half-life (label) | n/a | Thereafter, metaxalone concentrations decline log-linearly with a terminal half-life of 9.0 ± 4.8 hours. |
| Earliest approval on file (Drugs@FDA) | August 15, 1958 | August 13, 1962 |
| First generic approved | October 6, 1981 | March 31, 2010 |
| Generic labelers (NDC) | 19 labelers | 33 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.210 per tablet (Chlorzoxazone 500 mg tablet) | $0.452 per tablet (Metaxalone 800 mg tablet) |
| 12-month price change | -5% | -3% |
| Boxed warning | No | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 2 | 0 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 1,296 | 3,327 |
| 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?
Metaxalone label, warningsRisks from Concomitant Use with Alcohol or other CNS Depressants The sedative effects of metaxalone and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants (TCAs)) may be additive.
Source: FDA drug labels via openFDA
What next?
- Alternatives to chlorzoxazone
- every medicine labeled for the same conditions