What the FDA labels say about taking them together
Irinotecan and leucovorin
Irinotecan's FDA label of May 12, 2026 names leucovorin in its drug interactions section; the leucovorin labels PlainMeds reads (2) do not name irinotecan. The irinotecan label: “Strong CYP3A4 Inhibitors: Do not administer strong CYP3A4 inhibitors with CAMPTOSAR. 7.1 5-Fluorouracil (5-FU) and Leucovorin (LV) In a phase 1 clinical study involving irinotecan, 5-fluorouracil (5-FU), and leucovorin …”
Check it at the source: the irinotecan FDA label on DailyMed (effective May 12, 2026, Pharmacia & Upjohn Company LLC); the leucovorin FDA label on DailyMed (effective March 19, 2025, Meitheal Pharmaceuticals Inc.).
What does the irinotecan label say about leucovorin?
Irinotecan label, drug interactionsStrong CYP3A4 Inhibitors: Do not administer strong CYP3A4 inhibitors with CAMPTOSAR. ( 7.3 ) 7.1 5-Fluorouracil (5-FU) and Leucovorin (LV) In a phase 1 clinical study involving irinotecan, 5-fluorouracil (5-FU), and leucovorin (LV) in 26 patients with solid tumors, the disposition of irinotecan was not substantially altered when the drugs were co-administered.
Onivyde label (Ipsen Biopharmaceuticals, Inc., March 3, 2025), boxed warningSEVERE NEUTROPENIA AND SEVERE DIARRHEA Neutropenia Severe and life-threatening neutropenia, including fatal neutropenic sepsis and fatal neutropenic fever, has occurred in patients receiving ONIVYDE in combination with oxaliplatin, fluorouracil and leucovorin and in combination with fluorouracil and leucovorin.
Onivyde label (Ipsen Biopharmaceuticals, Inc., March 3, 2025), warnings and precautionsIn NAPOLI 3, Grade 3 and 4 neutropenia occurred in 26% of patients receiving ONIVYDE in combination with oxaliplatin, fluorouracil, and leucovorin (NALIRIFOX) and fatal neutropenic fever in 0.3% of patients [see Adverse Reactions (6.1) ].
Source: FDA drug label (Onivyde, NDA207793), Ipsen Biopharmaceuticals, Inc., effective March 3, 2025 (SPL set c8b58efa-1820-48a4-b70d-62918fc4abfc), via openFDA
Source: FDA drug label (Camptosar), NDA020571 (Pfizer Inc), as published by Pharmacia & Upjohn Company LLC, effective May 12, 2026 (SPL set e518dfc6-7e93-4fee-a66c-51e1ab71c056), via openFDA; the full label on DailyMed
What does the leucovorin label say about irinotecan?
Leucovorin's label (effective March 19, 2025) and its 1 other brand-application label do not name irinotecan in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (leucovorin calcium), Meitheal Pharmaceuticals Inc., effective March 19, 2025 (SPL set 9df20901-6980-4d4e-89ec-40f3c1f91852), 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
| Irinotecan | Leucovorin | |
|---|---|---|
| Labeled for | Colorectal cancer | Colorectal cancer |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $0.330 per tablet 5 mg tablet |
| Shortage now | A presentation being discontinued | 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