What the FDA labels say about taking them together
Cyclobenzaprine and morphine
Morphine's FDA label of July 13, 2026 names cyclobenzaprine in its drug interactions section; the cyclobenzaprine labels PlainMeds reads (3) do not name morphine. The morphine 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 cyclobenzaprine FDA label on DailyMed (effective February 21, 2025, Jubilant Cadista Pharmaceuticals Inc.); the morphine FDA label on DailyMed (effective July 13, 2026, Bryant Ranch Prepack).
What does the cyclobenzaprine label say about morphine?
Cyclobenzaprine's label (effective February 21, 2025) and its 2 other brand-application labels do not name morphine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cyclobenzaprine Hydrochloride), Jubilant Cadista Pharmaceuticals Inc., effective February 21, 2025 (SPL set 592871f6-0eb2-4624-9e10-bd8bf767c002), via openFDA; the full label on DailyMed
What does the morphine label say about cyclobenzaprine?
Morphine label, drug interactionsSerotonergic Drugs Clinical Impact: The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. … 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).
Source: FDA drug label (Ms Contin, NDA019516), Rhodes Pharmaceuticals LLC, effective August 14, 2026 (SPL set c354b3bf-86c0-4bb8-8b1f-be2164942698), via openFDA
Source: FDA drug label (Morphine sulfate), ANDA078761 (Sun Pharm Inds Ltd), as published by Bryant Ranch Prepack, effective July 13, 2026 (SPL set 595243fe-a4b1-479a-99d6-a084a4181891), 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
| Cyclobenzaprine | Morphine | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity, Nerve pain and fibromyalgia | Pain |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0171 per tablet 10 mg tablet | $0.226 per tablet 15 mg tablet |
| Shortage now | No current entry | In shortage |
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