Two medicines, side by side
Metaxalone vs tizanidine
Metaxalone and tizanidine are both labeled for muscle spasms and spasticity. Drugs@FDA records approvals of metaxalone since 1962 and of tizanidine since 1996. Pharmacies paid $0.452 per metaxalone 800 mg tablet and $0.0331 per tizanidine HCl 4 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, metaxalone is a muscle relaxant and tizanidine a central alpha-2 adrenergic agonist.
Check it at the source: the metaxalone FDA label on DailyMed (effective January 11, 2023); the tizanidine FDA label on DailyMed (effective January 2, 2026).
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
Highlights of the tizanidine record
Tizanidine (Zanaflex) · label of January 2, 2026
Used for
From the label: indicationsZanaflex is indicated for the treatment of spasticity in adults. Zanaflex is a central alpha-2-adrenergic agonist indicated for the treatment of spasticity.
On the market
- Earliest approval on file
- November 27, 1996
- Generic labelers
- 49 labelers
- Pharmacy cost
- $0.0331 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 9
Source: FDA drug labels via openFDA (Metaxalone label of January 11, 2023, Tizanidine label of January 2, 2026); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metaxalone and tizanidine differ on the record?
In FDA's classes, metaxalone is a muscle relaxant and tizanidine a central alpha-2 adrenergic agonist.
How each works, in its label's words: Metaxalone, “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.”; Tizanidine, “Tizanidine is a central alpha-2-adrenergic receptor agonist and presumably reduces spasticity by increasing presynaptic inhibition of motor neurons.”
Half-life, in each label's words: Metaxalone, “Thereafter, metaxalone concentrations decline log-linearly with a terminal half-life of 9.0 ± 4.8 hours.”; Tizanidine, “Elimination Metabolism Tizanidine has a half-life of approximately 2.5 hours (CV=33%).”
Generics: metaxalone since 2010; tizanidine since 2002 (Drugs@FDA).
| Metaxalone | Tizanidine | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity | Muscle spasms and spasticity |
| Pharmacologic class | Muscle Relaxant | Central alpha-2 Adrenergic Agonist |
| How it works (label) | 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. | Tizanidine is a central alpha-2-adrenergic receptor agonist and presumably reduces spasticity by increasing presynaptic inhibition of motor neurons. The effects of tizanidine are greatest on polysynaptic pathways. |
| Half-life (label) | Thereafter, metaxalone concentrations decline log-linearly with a terminal half-life of 9.0 ± 4.8 hours. | Elimination Metabolism Tizanidine has a half-life of approximately 2.5 hours (CV=33%). |
| Earliest approval on file (Drugs@FDA) | August 13, 1962 | November 27, 1996 |
| First generic approved | March 31, 2010 | June 27, 2002 |
| Generic labelers (NDC) | 33 labelers | 49 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.452 per tablet (Metaxalone 800 mg tablet) | $0.0331 per tablet (Tizanidine HCl 4 mg tablet) |
| 12-month price change | -3% | -12% |
| Boxed warning | No | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 0 | 9 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 3,327 | 41,179 |
| 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 metaxalone
- every medicine labeled for the same conditions