The most commonly used cytotoxic drug for nephrotic syndrome is cyclophosphamide, which is an immunosuppressant and an alkylating agent. This drug can destroy the structure and function of cellular DNA, inhibit cell division and proliferation, and is the most commonly used cytotoxic drug for the clinical treatment of primary nephrotic syndrome, and can be used orally or intravenously. Generally, for the treatment of nephrotic syndrome, the most common method is oral administration, and patients need to take a daily dose of 2 mg per kg of body weight in 2-3 doses. Patients with this drug generally need to reach a total of 6-12 g. Before using the drug, they need to drink more water and avoid taking the drug at bedtime. It is also necessary to monitor the various side effects of this drug, such as hemorrhagic cystitis, bone marrow suppression, liver function impairment, etc. This is a drug that has quite obvious side effects on the human body and needs to be used strictly in accordance with medical advice. Newer immunosuppressive drugs are now also available, including cyclosporine, tacrolimus, mycophenolate, etc.