Abstract: Although immune checkpoint inhibitors (ICI) can significantly improve the clinical prognosis of patients with advanced solid tumors, a considerable number of patients still can't benefit from ICI treatment. In clinical practice, lots of drugs such as antibiotics, glucocorticoids, proton pump inhibitors and β receptor blockers can affect the antitumor effect of ICI drugs through different mechanisms. Antibiotics and proton pump inhibitors may inhibit the therapeutic effect of ICI by affecting intestinal flora, and β receptor blockers may enhance tumor sensitivity to ICI therapy by inhibiting β adrenoceptor signaling pathway. The effect of glucocorticoid on the therapeutic effect of ICI may depend on its indications, such as tumor/non-tumor related symptoms and immunotherapy related side effects. This study reviewed the related researches on the above clinical drugs in ICI treatment, in order to provide a theoretical basis for optimizing the individualized treatment strategy of ICI in patients with advanced tumors.