What the FDA labels say about taking them together
Cladribine and ritonavir
Cladribine's FDA label of May 27, 2026 names ritonavir in its drug interactions section; the ritonavir label PlainMeds reads does not name cladribine. The cladribine label: “Prevention or Management; Avoid co-administration of potent ENT1, CNT3, or BCRP transporter inhibitors during the 4 to 5 day MAVENCLAD treatment cycles. …”
Check it at the source: the cladribine FDA label on DailyMed (effective May 27, 2026, EMD Serono, Inc.); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the cladribine label say about ritonavir?
Cladribine label, drug interactionsPrevention or Management; Avoid co-administration of potent ENT1, CNT3, or BCRP transporter inhibitors (e.g., ritonavir, eltrombopag, curcumin, cyclosporine, dilazep, nifedipine, nimodipine, cilostazol, sulindac, dipyridamole, or reserpine) during the 4 to 5 day MAVENCLAD treatment cycles. If this is not possible, consider selection of alternative concomitant drugs with no or minimal ENT1, CNT3, or BCRP transporter inhibiting properties. If this is not possible, dose reduction to the minimum mandatory dose of drugs containing these compounds, separation in the timing of administration, and careful patient monitoring is recommended.
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 ritonavir label say about cladribine?
Ritonavir's label (effective July 23, 2026) does not name cladribine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), 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 | Ritonavir | |
|---|---|---|
| Labeled for | Multiple sclerosis, Leukemia, lymphoma and myeloma | HIV |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | n/a | $0.607 per tablet 100 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
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