What the FDA labels say about taking them together
Ritonavir and tacrolimus
Ritonavir's FDA label of July 23, 2026 names tacrolimus in its drug interactions section, and tacrolimus's label names ritonavir too. The ritonavir label: “Therapeutic concentration monitoring is recommended for immunosuppressant agents when co-administered with ritonavir.”
Check it at the source: the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.); the tacrolimus FDA label on DailyMed (effective July 17, 2026, Stellon Biotech Inc.).
What does the ritonavir label say about tacrolimus?
Ritonavir label, drug interactionsConcomitant Drug Class/Drug Name: Immunosuppressants: cyclosporine, tacrolimus, sirolimus (rapamycin); Effect on Concentration of Ritonavir or Concomitant Drug: ↑ immunosuppressants; Clinical Comment: Therapeutic concentration monitoring is recommended for immunosuppressant agents when co-administered with ritonavir.
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
What does the tacrolimus label say about ritonavir?
Tacrolimus label, drug interactionsDrug/Substance Class or Name: Strong CYP3A Inhibitors 3: Protease inhibitors (e.g, nelfinavir, telaprevir, boceprevir, ritonavir), azole antifungals (e.g., voriconazole, posaconazole, itraconazole, ketoconazole), antibiotics (e.g., clarithromycin, troleandomycin, chloramphenicol), nefazodone, letermovir, Schisandra sphenanthera extracts; Drug Interaction Effect: May increase tacrolimus whole blood trough concentrations and increase the risk of serious adverse reactions (e.g., neurotoxicity, QT prolongation). A rapid, sharp rise in tacrolimus levels may occur early, despite an immediate reduction of tacrolimus dose [see,,)].; …
Tacrolimus label, warnings and precautionsInhibitors and Inducers When co-administering tacrolimus with strong CYP3A4 inhibitors (e.g., telaprevir, boceprevir, ritonavir, ketoconazole, itraconazole, voriconazole, clarithromycin) and strong inducers (e.g., rifampin, rifabutin), adjustments in the dosing regimen of tacrolimus and subsequent frequent monitoring of tacrolimus whole blood trough concentrations and tacrolimus-associated adverse reactions are recommended.
Astagraf Xl label (Astellas Pharma US, Inc., January 14, 2026), warnings and precautionsTherefore, adjust ASTAGRAF XL dose and monitor tacrolimus whole blood trough concentrations when co-administering ASTAGRAF XL with strong CYP3A inhibitors (e.g., including, but not limited to, telaprevir, boceprevir, ritonavir, ketoconazole, itraconazole, voriconazole, clarithromycin) or strong CYP3A inducers (e.g., including, but not limited to, rifampin, rifabutin) [see Dosage and Administration ( 2.4 ) and Drug Interactions ( 7.2 )].
Source: FDA drug label (Prograf, NDA050708), Astellas Pharma US, Inc., effective August 25, 2023 (SPL set 7f667de1-9dfa-4bd6-8ba0-15ee2d78873b), via openFDA
Source: FDA drug label (Tacrolimus), Stellon Biotech Inc., effective July 17, 2026 (SPL set 6b89e8a4-9f11-42e3-8e79-fe617e7c461f), 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
| Ritonavir | Tacrolimus | |
|---|---|---|
| Labeled for | HIV | Organ transplant rejection, Eczema (atopic dermatitis) |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.607 per tablet 100 mg tablet | $0.970 per gram 0.1% ointment |
| 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