What the FDA labels say about taking them together
Buprenorphine and metaxalone
Buprenorphine's FDA label of June 5, 2026 names metaxalone in its drug interactions section; the metaxalone labels PlainMeds reads (2) do not name buprenorphine. The buprenorphine 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 buprenorphine FDA label on DailyMed (effective June 5, 2026); the metaxalone FDA label on DailyMed (effective January 11, 2023, Amneal Pharmaceuticals of New York LLC).
What does the buprenorphine label say about metaxalone?
Buprenorphine label, drug interactionsClinical 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 (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue).
Sublocade label (Indivior Inc., July 27, 2026), drug interactionsClinical 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 (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue).
Source: FDA drug label (Brixadi, NDA210136), Braeburn Inc., effective December 31, 2025 (SPL set 5d8a8fd0-8619-422a-a664-d1d2e8970f48), via openFDA
Source: FDA drug label (Butrans, NDA021306), Knoa Pharma LLC, effective May 1, 2026 (SPL set 794aa355-66de-41b8-aedf-f2c40f6bc664), via openFDA
Source: FDA drug label (Sublocade, NDA209819), Indivior Inc., effective July 27, 2026 (SPL set 6189fb21-9432-45f8-8481-0bfaf3ccde95), via openFDA
Source: FDA drug label (Buprenorphine HCl), SpecGx LLC, effective June 5, 2026 (SPL set b60d514d-a88a-4fa2-a5b0-30ac29e04973), via openFDA; the full label on DailyMed
What does the metaxalone label say about buprenorphine?
Metaxalone's label (effective January 11, 2023) and its 1 other brand-application label do not name buprenorphine 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
| Buprenorphine | Metaxalone | |
|---|---|---|
| Labeled for | Opioid use disorder, Pain | Muscle spasms and spasticity |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.277 per tablet 2 mg tablet sl | $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