Cetuximab injection, due to different conditions, individual differences in sensitivity to the drug, the onset of effect time is uncertain, and the effect should be evaluated according to the actual situation after the use of the drug. Cetuximab injection is mostly used in the treatment of metastatic colorectal cancer. It can be used alone or combined with irinotecan. Generally, its serum concentration tends to a steady state and begins to see the effect slowly starting from the third week after the injection alone. The injection is given at an initial dose of 400mg/m² body surface area and subsequent weekly doses of 250mg/m² body surface area. Common adverse reactions after injection include headache, conjunctivitis, nausea, and vomiting. Dehydration and pulmonary embolism may occur in some people. Serious adverse reactions need to be treated by informing the doctor immediately. It is important to note that the drug must be used under the supervision of a physician experienced in the use of anticancer drugs. It is also contraindicated in people with known severe hypersensitivity to cetuximab. In addition, contraindications related to irinotecan should be considered if combination therapy is required.