What the FDA labels say about taking them together
Cyclobenzaprine and phenelzine
Phenelzine's FDA label of June 6, 2025 names cyclobenzaprine in its warnings section; cyclobenzaprine's label does not name phenelzine itself but warns about its class (MAO inhibitors).
Check it at the source: the cyclobenzaprine FDA label on DailyMed (effective February 21, 2025, Jubilant Cadista Pharmaceuticals Inc.); the phenelzine FDA label on DailyMed (effective June 6, 2025, Parke-Davis Div of Pfizer Inc).
What does the cyclobenzaprine label say about phenelzine?
Cyclobenzaprine's label does not name phenelzine itself; it warns about its class (MAO inhibitors):
Cyclobenzaprine label, warningsWARNINGS Serotonin Syndrome The development of a potentially life-threatening serotonin syndrome has been reported with cyclobenzaprine hydrochloride when used in combination with other drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), tramadol, bupropion, meperidine, verapamil, or MAO inhibitors.
Cyclobenzaprine label, contraindicationsHyperpyretic crisis seizures, and deaths have occurred in patients receiving cyclobenzaprine (or structurally similar tricyclic antidepressants) concomitantly with MAO inhibitor drugs.
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 phenelzine label say about cyclobenzaprine?
Phenelzine label, warningsA List of Dibenzazepine Derivative Drugs by Generic Name Follows: nortriptyline hydrochloride amitriptyline hydrochloride perphenazine and amitriptyline hydrochloride clomipramine hydrochloride desipramine hydrochloride imipramine hydrochloride doxepin carbamazepine cyclobenzaprine HCl amoxapine maprotiline HCl trimipramine maleate protriptyline HCl mirtazapine NARDIL should be used with caution in combination with antihypertensive drugs, including thiazide diuretics and β-blockers, since exaggerated hypotensive effects may result.
Source: FDA drug label (Nardil), Parke-Davis Div of Pfizer Inc, effective June 6, 2025 (SPL set 513a41d0-37d4-4355-8a6d-a2c643bce6fa), 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 | Phenelzine | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity, Nerve pain and fibromyalgia | n/a |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0171 per tablet 10 mg tablet | $0.586 per tablet 15 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