High eosinophils are not necessarily an allergy, but they certainly do not rule out allergies. High eosinophils can be caused by many reasons, including parasitic diseases, allergic diseases and skin diseases. 1. Parasitic diseases: the most common cause of eosinophilia, eosinophilia in the blood can reach 10% or more. 2. Allergic diseases: such as bronchial asthma, necrotizing vasculitis, drug allergic reaction, urticaria, allergy to foreign proteins, hay fever and so on. 3. Skin diseases: such as exfoliative dermatitis, eczema, pemphigus, psoriasis, etc. 4. In addition to the above reasons, hematological diseases (such as chronic granulocytic leukemia, etc.), infectious diseases (such as scarlet fever, etc.), and certain malignant tumors (such as lung cancer) can also cause elevated eosinophils. If eosinophils are high and there are uncomfortable symptoms, it is recommended to go to the hospital in time to determine the cause of the disease as soon as possible and carry out regular treatment under the guidance of the doctor.