What the FDA labels say about taking them together
Levorphanol and metaxalone
Levorphanol's FDA label of January 13, 2026 names metaxalone in its drug interactions section; metaxalone's label does not name levorphanol itself but warns about its class (Opioids (opioid agonists)). The levorphanol label: “Serotonergic Drugs The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system, such as selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake …”
Check it at the source: the levorphanol FDA label on DailyMed (effective January 13, 2026, Sun Pharmaceutical Industries, Inc.); the metaxalone FDA label on DailyMed (effective January 11, 2023, Amneal Pharmaceuticals of New York LLC).
What does the levorphanol label say about metaxalone?
Levorphanol label, drug interactionsSerotonergic Drugs The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system, such as selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that affect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), and monoamine oxidase (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue), has resulted in serotonin syndrome. [see PRECAUTIONS;
Source: FDA drug label (Levorphanol Tartrate), Sun Pharmaceutical Industries, Inc., effective January 13, 2026 (SPL set 438cf3ea-04fe-4626-9f0f-adcda7633651), via openFDA; the full label on DailyMed
What does the metaxalone label say about levorphanol?
Metaxalone's label does not name levorphanol 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
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
| Levorphanol | Metaxalone | |
|---|---|---|
| Labeled for | Pain | Muscle spasms and spasticity |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $10.65 per tablet 2 mg tablet | $0.452 per tablet 800 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