What the FDA labels say about taking them together
Metaxalone and tapentadol
Tapentadol's FDA label of February 26, 2026 names metaxalone in its drug interactions section; metaxalone's label does not name tapentadol itself but warns about its class (Opioids (opioid agonists)). The tapentadol label: “The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.”
Check it at the source: the metaxalone FDA label on DailyMed (effective January 11, 2023, Amneal Pharmaceuticals of New York LLC); the tapentadol FDA label on DailyMed (effective February 26, 2026, Hikma Pharmaceuticals USA Inc.).
What does the metaxalone label say about tapentadol?
Metaxalone's label does not name tapentadol itself; it warns about its class (Opioids (opioid agonists)):
Metaxalone label, warnings and precautionsCases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of metaxalone (within the recommended dosage range) and other serotonergic drugs [see Drug Interactions (7) ] and with the use of metaxalone as the only serotonergic drug taken at a dosage higher than the recommended dosage [see Overdosage (10) ]. …
Metaxalone label, drug interactionsDiscontinue metaxalone if serotonin syndrome is suspected. Examples of serotonergic drugs include: selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, opioids (particularly fentanyl, meperidine, and methadone), drugs that affect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), monoamine oxidase (MAO) inhibitors (those intended to treat psychiatric disorders …
Source: FDA drug label (Metaxalone), Amneal Pharmaceuticals of New York LLC, effective January 11, 2023 (SPL set f06f2b96-3684-483c-89f7-6c9201fd4664), via openFDA; the full label on DailyMed
What does the tapentadol label say about metaxalone?
Tapentadol label, drug interactionsSerotonergic Drugs Clinical Impact: The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. … neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), monoamine oxidase inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue).
Tapentadol label, warnings and precautionsSerotonergic drugs include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that affect the serotonergic neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), and drugs that impair metabolism of serotonin (including monoamine oxidase inhibitors, both those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue) [see Drug Interactions (7) ].
Source: FDA drug label (TAPENTADOL), Hikma Pharmaceuticals USA Inc., effective February 26, 2026 (SPL set 863f3fd3-1e8d-41b0-855f-8f9a29237cda), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Metaxalone | Tapentadol | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity | Pain |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.452 per tablet 800 mg tablet | $14.48 per tablet 100 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once