What the FDA labels say about taking them together
Butorphanol and metaxalone
Butorphanol's FDA label of January 2, 2026 names metaxalone in its drug interactions section; the metaxalone labels PlainMeds reads (2) do not name butorphanol. The butorphanol 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 butorphanol FDA label on DailyMed (effective January 2, 2026, Hospira, Inc.); the metaxalone FDA label on DailyMed (effective January 11, 2023, Amneal Pharmaceuticals of New York LLC).
What does the butorphanol label say about metaxalone?
Butorphanol 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 (eg., 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 (Butorphanol Tartrate), Hospira, Inc., effective January 2, 2026 (SPL set 9822ca3f-aee2-46e5-8a96-495400e65d10), via openFDA; the full label on DailyMed
What does the metaxalone label say about butorphanol?
Metaxalone's label (effective January 11, 2023) and its 1 other brand-application label do not name butorphanol in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Butorphanol | Metaxalone | |
|---|---|---|
| Labeled for | Pain | Muscle spasms and spasticity |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $15.46 per mL 10 mg/mL spray | $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