The following adverse reactions are discussed in greater detail in other sections of the label: Cardiomyopathy Embryo-Fetal Toxicity Pulmonary Toxicity Exacerbation of Chemotherapy-Induced Neutropenia Hypersensitivity and Administration-Related Reactions Adjuvant Breast Cancer Most common adverse reactions (≥10%) for HERCEPTIN HYLECTA are fatigue, arthralgia, diarrhea, injection site reaction, upper respiratory tract infection, rash, myalgia, nausea, headache, edema, flushing, pyrexia, cough, and pain in extremity. Metastatic Breast Cancer (based on intravenous trastuzumab) Most common adverse reactions (≥10%) are fever, chills, headache, infection, congestive heart failure, insomnia, cough, and rash.