What the FDA labels say about taking them together
Fostamatinib and ritonavir
Ritonavir's FDA label of July 23, 2026 names fostamatinib in its drug interactions section; the fostamatinib label PlainMeds reads does not name ritonavir. The ritonavir label: “Monitor for toxicities of R406 exposure resulting in dose-related adverse events such as hepatotoxicity and neutropenia. Fostamatinib dose reduction may be required.”
Check it at the source: the fostamatinib FDA label on DailyMed (effective November 5, 2025, Rigel Pharmaceuticals, Inc.); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the fostamatinib label say about ritonavir?
Fostamatinib's label (effective November 5, 2025) does not name ritonavir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (TAVALISSE), Rigel Pharmaceuticals, Inc., effective November 5, 2025 (SPL set 21149cc3-049b-43e2-b141-c9499160556c), via openFDA; the full label on DailyMed
What does the ritonavir label say about fostamatinib?
Ritonavir label, drug interactionsConcomitant Drug Class/Drug Name: Kinase Inhibitors: fostamatinib (also see anticancer agents above); Effect on Concentration of Ritonavir or Concomitant Drug: ↑ fostamatinib metabolite R406; Clinical Comment: Monitor for toxicities of R406 exposure resulting in dose-related adverse events such as hepatotoxicity and neutropenia. Fostamatinib dose reduction may be required.
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
| Fostamatinib | Ritonavir | |
|---|---|---|
| Labeled for | n/a | HIV |
| Boxed warning | No | 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