Leukemia varies depending on the type and how long it takes to show symptoms. It can last from a few days to several years. The onset of leukemia can be insidious, slow, or acute. Generally, acute leukemia will show symptoms in a short period of time after diagnosis, while chronic leukemia will take a longer period of time, and some patients need several months or even years to show symptoms. 1. Acute leukemia: 70% of the patients have anemia as the first manifestation, often with progressive aggravation. 50% of the patients have fever as the early manifestation, mainly due to infection. Generally, the above symptoms can be seen within a few days after the onset of the disease. 2. Chronic leukemia: for example, chronic granulocytic leukemia, most of the patients have slow onset of the disease, and there are often no conscious symptoms in the early stage, and the patients can be diagnosed due to physical examination or checking for other diseases before they find the abnormalities in blood count or splenomegaly. Some patients may show non-specific symptoms such as fatigue, weight loss, excessive sweating, low fever, etc., which are detected only after examination. Some patients have relevant symptoms only after several months or even years. Therefore, the symptomatic manifestation of leukemia may be manifested at different times depending on the mildness, severity, slowness and urgency of the disease. Specific diagnosis and treatment should be carried out under the guidance of a physician.