What the FDA labels say about taking them together
Metaxalone and methylene blue
Metaxalone's FDA label of January 11, 2023 names methylene blue in its drug interactions section; the methylene blue label PlainMeds reads does not name metaxalone. The metaxalone label: “Serotonergic drugs include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, opioids …”
Check it at the source: the metaxalone FDA label on DailyMed (effective January 11, 2023, Amneal Pharmaceuticals of New York LLC); the methylene blue FDA label on DailyMed (effective May 28, 2025, American Regent, Inc.).
What does the metaxalone label say about methylene blue?
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 and also others, such as linezolid and intravenous methylene blue).
Metaxalone label, warningsSerotonergic 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 serotonergic neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), and drugs that impair metabolism of serotonin (including monoamine oxidase (MAO) inhibitors, both those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue) (see PRECAUTIONS:
Source: FDA drug label (Metaxalone, NDA022503), INA Pharmaceutics Inc, effective February 3, 2026 (SPL set fc6de1a6-26aa-47ac-a5d2-bf127a6ca563), via openFDA
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 methylene blue label say about metaxalone?
Methylene blue's label (effective May 28, 2025) does not name metaxalone in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (PROVAYBLUE), NDA204630 (Provepharm Sas), as published by American Regent, Inc., effective May 28, 2025 (SPL set 4f6848e5-35ed-4046-b13c-3032b5ba3232), 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 | Methylene blue | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity | n/a |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.452 per tablet 800 mg tablet | n/a |
| 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