The side effects of stem cell transplantation are fever, rejection reaction, etc. However, not all patients will experience side effects and it is impossible to generalize. Stem cell transplantation is a common clinical treatment for diseases, which is to infuse autologous or allogeneic hematopoietic stem cells with proliferative function back into the body, so as to achieve the purpose of repairing senescent diseased cells, as well as rebuilding normal functioning cells and tissues. Generally, after stem cell transplantation, patients may experience the side effect of fever for a short period of time, usually after a few hours, the body temperature will gradually return to the normal level and there is no need to worry too much. However, it is important to note that some patients may experience rejection reactions, with severe symptoms such as gastrointestinal bleeding, pulmonary hemorrhage, interstitial pneumonia, and renal failure, which may be life-threatening and need to be taken seriously. After stem cell transplantation, patients need to ensure sufficient sleep time and do not overwork. If they feel unwell, they should consult a doctor in time.