Generic name of Herceptin is Trastuzumab for Injection, and there are many side effects of the targeted therapy, such as cardiovascular adverse effects, dyspnea, and allergy, which are related to the patient’s health condition. Trastuzumab for Injection is an active ingredient that selectively acts on HER-2 cells. During targeted therapy, the expression of HER-2 protein can be inhibited by the use of trastuzumab, thus achieving the purpose of controlling the development of the disease. However, since different patients have different physical conditions, some side effects may occur during use. 1. Cardiovascular adverse reactions: it may affect the cardiovascular system, which may lead to a series of uncomfortable symptoms, such as cardiac insufficiency, heart failure and so on. 2. Dyspnea: may cause damage to the respiratory system, which may lead to dyspnea, and in severe cases, may even lead to respiratory failure and other problems. 3. Allergy: over time, the immune system may be affected, thus triggering a variety of allergic reactions, such as nausea, vomiting, skin redness and swelling, etc., and the efficacy of the medication will also decrease. Therefore, in the process of medication, patients need to go to the hospital for regular checkups and timely assessment of the medication. If the symptoms are minor, such as loss of appetite, they can be left alone for the time being, but if the symptoms are more pronounced, the medication should be stopped as soon as possible, and the treatment should be adjusted under the guidance of the doctor.