Cyclophosphamide and Trastuzumab interaction
Cyclophosphamide and Trastuzumab: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Trastuzumab (Trazimera) label · effective 2026-04-10
AC Anthracycline (doxorubicin) and cyclophosphamide. → Paclitaxel+Trastuzumab 3.2% (64/2000) Includes 1 patient with fatal cardiomyopathy and 1 patient with sudden death without documented etiology.
Table 2: Incidence of Cardiac Dysfunction Congestive heart failure or significant asymptomatic decrease in LVEF. in Metastatic Breast Cancer Studies Incidence NYHA I–IV NYHA III–IV Study Event Trastuzumab Control Trastuzumab Control H0648g (AC) Anthracycline (doxorubicin or epirubicin) and cyclophosphamide.
In NSABP B31, 15% (158/1031) of patients discontinued trastuzumab due to clinical evidence of myocardial dysfunction or significant decline in LVEF after a median follow-up duration of 8.7 years in the AC-TH (anthracycline, cyclophosphamide, paclitaxel, and trastuzumab) arm.
From the Cyclophosphamide (Frindovyx) label · effective 2026-08-26
…administered after paclitaxel infusion. ● Thiazide diuretics ● Zidovudine Increased cardiotoxicity ● Anthracyclines ● Cytarabine ● Pentostatin ● Radiation therapy of the cardiac region ● Trastuzumab Increased pulmonary toxicity ● Amiodarone ● G-CSF, GM-CSF (granulocyte colony-stimulating factor, granulocyte macrophage colony-stimulating factor) Increased nephrotoxicity…
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.