What the FDA labels say about taking them together
Cysteamine and penicillamine
Cysteamine's FDA label (Procysbi) of June 25, 2026 names penicillamine in its contraindications section; the penicillamine labels PlainMeds reads (2) do not name cysteamine. The cysteamine label: “CONTRAINDICATIONS CYSTAGON ® is contraindicated in patients who have developed hypersensitivity to it or to cysteamine or penicillamine.”
Check it at the source: the cysteamine FDA label on DailyMed (effective April 30, 2025, Leadiant Biosciences, Inc.); the penicillamine FDA label on DailyMed (effective January 26, 2026, Bausch Health US, LLC).
What does the cysteamine label say about penicillamine?
Procysbi label (Horizon Therapeutics USA, Inc., June 25, 2026), contraindicationsCONTRAINDICATIONS The use of PROCYSBI is contraindicated in patients with a serious hypersensitivity reaction, including anaphylaxis, to penicillamine or cysteamine. Hypersensitivity to penicillamine or cysteamine
Cystagon label (Mylan Pharmaceuticals Inc., August 16, 2021), contraindicationsCONTRAINDICATIONS CYSTAGON ® is contraindicated in patients who have developed hypersensitivity to it or to cysteamine or penicillamine.
Source: FDA drug label (Procysbi, NDA203389), Horizon Therapeutics USA, Inc., effective June 25, 2026 (SPL set d3a3ec28-f746-463a-bb92-3bc8826db09e), via openFDA
Source: FDA drug label (Cystagon, NDA020392), Mylan Pharmaceuticals Inc., effective August 16, 2021 (SPL set f495b76d-96c6-48e5-8fa3-30a4336628eb), via openFDA
Source: FDA drug label (CYSTARAN), Leadiant Biosciences, Inc., effective April 30, 2025 (SPL set b98ee838-ed23-42a9-93b5-72579e490fba), via openFDA; the full label on DailyMed
What does the penicillamine label say about cysteamine?
Penicillamine's label (effective January 26, 2026) and its 1 other brand-application label do not name cysteamine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cuprimine), NDA019853 (Valeant Pharms Intl), as published by Bausch Health US, LLC, effective January 26, 2026 (SPL set 80e736d3-2017-4d68-94b4-38255c3c59c6), 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
| Cysteamine | Penicillamine | |
|---|---|---|
| Labeled for | n/a | Rheumatoid arthritis |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | 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