What the FDA labels say about taking them together
Methylene blue and naloxone/pentazocine
Naloxone/pentazocine's FDA label of August 28, 2025 names methylene blue in its drug interactions section; the methylene blue label PlainMeds reads does not name naloxone/pentazocine. The naloxone/pentazocine 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 methylene blue FDA label on DailyMed (effective May 28, 2025, American Regent, Inc.); the naloxone/pentazocine FDA label on DailyMed (effective August 28, 2025, Lupin Pharmaceuticals,Inc.).
What does the methylene blue label say about naloxone/pentazocine?
Methylene blue's label (effective May 28, 2025) does not name naloxone/pentazocine 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
What does the naloxone/pentazocine label say about methylene blue?
Naloxone/pentazocine 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), 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 (PENTAZOCINE HYDROCHLORIDE AND NALOXONE HYDROCHLORIDE), Lupin Pharmaceuticals,Inc., effective August 28, 2025 (SPL set 017ef042-40aa-44c9-baa8-037f06356845), 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
| Methylene blue | Naloxone/pentazocine | |
|---|---|---|
| Labeled for | n/a | Pain |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | n/a | $2.06 per tablet Pentazocine-naloxone 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