EGFR and breast cancer: According to the “Expert consensus on the management of adverse events of ErbB family tyrosine kinase inhibitors (TKI) in breast cancer”, diarrhea caused by small-molecule TKIs targeting the HER2 receptor should be treated with an initial dose of 4 mg of loperamide, followed by 2 mg every 2 h, up to a maximum of 16 mg (Wang et al., 2020).