What the FDA labels say about taking them together
Fenfluramine and phentermine
Phentermine's FDA label of April 18, 2024 names fenfluramine in its warnings and precautions section; the fenfluramine label PlainMeds reads does not name phentermine.
Check it at the source: the fenfluramine FDA label on DailyMed (effective October 27, 2025, UCB, Inc.); the phentermine FDA label on DailyMed (effective April 18, 2024, KVK-Tech, Inc.).
What does the fenfluramine label say about phentermine?
Fenfluramine's label (effective October 27, 2025) does not name phentermine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Fintepla), NDA212102 (Ucb Inc), as published by UCB, Inc., effective October 27, 2025 (SPL set e88f360e-33ad-4cd6-b2de-5ef885857c5d), via openFDA; the full label on DailyMed
What does the phentermine label say about fenfluramine?
Phentermine label, warnings and precautionsHypertension (PPH) – a rare, frequently fatal disease of the lungs – has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine.
Source: FDA drug label (Phentermine Hydrochloride), KVK-Tech, Inc., effective April 18, 2024 (SPL set b963f7bb-fa65-4e28-81c9-282fbe70a6a6), 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
| Fenfluramine | Phentermine | |
|---|---|---|
| Labeled for | n/a | Weight management |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $0.0727 per tablet 37.5 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