What the FDA labels say about taking them together
Rifabutin and temsirolimus
Temsirolimus's FDA label of December 26, 2025 names rifabutin in its warnings and precautions section; the rifabutin label PlainMeds reads does not name temsirolimus. The temsirolimus label: “… such as dexamethasone, carbamazepine, phenytoin, phenobarbital, rifampin, rifabutin, and rifampacin may decrease exposure of the active metabolite, sirolimus.”
Check it at the source: the rifabutin FDA label on DailyMed (effective September 1, 2026, REMEDYREPACK INC.); the temsirolimus FDA label on DailyMed (effective December 26, 2025, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.).
What does the rifabutin label say about temsirolimus?
Rifabutin's label (effective September 1, 2026) does not name temsirolimus in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Rifabutin), NDA050689 (Pfizer), as published by REMEDYREPACK INC., effective September 1, 2026 (SPL set 25a60937-cbbe-4a50-994f-2ce15203f589), via openFDA; the full label on DailyMed
What does the temsirolimus label say about rifabutin?
Temsirolimus label, warnings and precautionsInducers or Inhibitors of CYP3A Metabolism Agents Inducing CYP3A Metabolism: Strong inducers of CYP3A4/5 such as dexamethasone, carbamazepine, phenytoin, phenobarbital, rifampin, rifabutin, and rifampacin may decrease exposure of the active metabolite, sirolimus.
Source: FDA drug label (Torisel), NDA022088 (Pf Prism Cv), as published by Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective December 26, 2025 (SPL set 95b7dc92-2180-42f1-8699-3c28f609e674), 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
| Rifabutin | Temsirolimus | |
|---|---|---|
| Labeled for | n/a | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $8.14 per capsule 150 mg capsule | 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