What the FDA labels say about taking them together
Trastuzumab and trastuzumab emtansine
Trastuzumab emtansine's FDA label of April 1, 2026 names trastuzumab in its warnings and precautions section; the trastuzumab labels PlainMeds reads (4) do not name trastuzumab emtansine. The trastuzumab emtansine label: “Treatment with KADCYLA has not been studied in patients who had trastuzumab permanently discontinued due to infusion-related reactions (IRRs) and/or hypersensitivity; …”
Check it at the source: the trastuzumab FDA label on DailyMed (effective May 29, 2026, Genentech, Inc.); the trastuzumab emtansine FDA label on DailyMed (effective April 1, 2026).
What does the trastuzumab label say about trastuzumab emtansine?
Trastuzumab's label (effective May 29, 2026) and its 3 other brand-application labels do not name trastuzumab emtansine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Herceptin), Genentech, Inc., effective May 29, 2026 (SPL set 492dbdb2-077e-4064-bff3-372d6af0a7a2), via openFDA; the full label on DailyMed
What does the trastuzumab emtansine label say about trastuzumab?
Trastuzumab emtansine label, warnings and precautionsTreatment with KADCYLA has not been studied in patients who had trastuzumab permanently discontinued due to infusion-related reactions (IRRs) and/or hypersensitivity; treatment with KADCYLA is not recommended for these patients.
Source: FDA drug label (KADCYLA), Genentech, Inc., effective April 1, 2026 (SPL set 23f3c1f4-0fc8-4804-a9e3-04cf25dd302e), 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
| Trastuzumab | Trastuzumab emtansine | |
|---|---|---|
| Labeled for | Breast cancer | Breast cancer |
| Boxed warning | Yes | Yes |
| 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