Eosinophils belong to one of the leukocyte tests with a reference value of 0.5%-5% and an absolute value of (0.05-0.5)×10^9/L. If the eosinophil percentage is high, consider that it may be related to allergic diseases, parasitic diseases, skin diseases, etc., which need to be treated for different triggers: 1. Allergic diseases: When patients have allergic diseases, due to allergen stimulation. such as food, drugs, dust, etc., may lead to high eosinophil percentage, such as urticaria, bronchial asthma, allergic rhinitis, etc. Patients with urticaria may have high eosinophil percentages along with itchy skin on the extremities and trunk, while patients with bronchial asthma and allergic rhinitis may have high eosinophil percentages along with wheezing, runny nose and cough. Patients can combine blood tests, erythrocyte sedimentation rate, C-reactive protein and other tests to clarify the specific cause of the disease. Usually, they can recover gradually after avoiding allergen stimulation or applying antihistamines, such as cetirizine and loratadine, for treatment. 2. Parasitic diseases: High eosinophil percentage may also be related to parasitic diseases, such as ascariasis, hookworm disease and schistosomiasis, which are usually associated with low immunity and poor sanitary environment of patients, often manifesting as indigestion, abdominal pain, diarrhea and other symptoms, requiring further judgment through pathogenic examination, imaging examination, and can choose anthelmintic drugs, such as albendazole for treatment; 3, skin diseases: some patients do not pay attention to personal hygiene and cleanliness, or due to inflammatory skin attack and other reasons, causing skin diseases, such as eczema, dermatitis, psoriasis, etc., can also be seen in patients with high percentage of eosinophils in the blood, while skin itching, erythema or papules can occur The patient can usually choose drug treatment, such as glucocorticoid ointment, antifungal ointment, etc.; 4, other diseases: patients with high eosinophil percentage may also be related to other pathological factors, such as leukemia, etc., which may be accompanied by local pain, generalized fever and other symptoms, according to the patient’s clinical symptoms and blood biochemical examination, bone marrow biopsy, etc., under the guidance of the doctor, the primary lesion for targeted The patient can be treated with targeted medication, chemotherapy or even hematopoietic stem cell transplantation under the guidance of the doctor. It is usually not possible to determine the cause of eosinophilia by the test result alone, but it is necessary to combine it with other indicators and symptoms to make a diagnosis, and to improve other tests if necessary to confirm the cause of the disease.