What the FDA labels say about taking them together
Cladribine and doravirine/islatravir
Doravirine/islatravir's FDA label of April 20, 2026 names cladribine in its drug interactions section; the cladribine label PlainMeds reads does not name doravirine/islatravir. The doravirine/islatravir label: “Co-administration with these nucleoside antimetabolites is not recommended as dCK substrates may cause a decrease in the intracellular concentration of ISL-TP.”
Check it at the source: the cladribine FDA label on DailyMed (effective May 27, 2026, EMD Serono, Inc.); the doravirine/islatravir FDA label on DailyMed (effective April 20, 2026, Merck Sharp & Dohme LLC).
What does the cladribine label say about doravirine/islatravir?
Cladribine's label (effective May 27, 2026) does not name doravirine/islatravir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Mavenclad), EMD Serono, Inc., effective May 27, 2026 (SPL set 9c75e30a-a410-40f1-b653-04d532bd9144), via openFDA; the full label on DailyMed
What does the doravirine/islatravir label say about cladribine?
Doravirine/islatravir label, drug interactionsConcomitant Drug Class/Drug Name: Nucleoside Antimetabolites cladribine clofarabine cytarabine fludarabine gemcitabine; Effect on Concentration: ↓ ISL-TP; Clinical Comment: Co-administration with these nucleoside antimetabolites is not recommended as dCK substrates may cause a decrease in the intracellular concentration of ISL-TP.
Source: FDA drug label (IDVYNSO), NDA216964 (Msd), as published by Merck Sharp & Dohme LLC, effective April 20, 2026 (SPL set 11aaeb53-9848-433c-be7f-db8a5bc0b26f), 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
| Cladribine | Doravirine/islatravir | |
|---|---|---|
| Labeled for | Multiple sclerosis, Leukemia, lymphoma and myeloma | HIV |
| Boxed warning | Yes | No |
| 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