The child’s fever of 40 degrees belongs to the manifestation of high fever, which may be caused by acute tonsillitis, urinary tract infection or other blood system diseases, and the patient can be relieved by general treatment, medication and other ways. 1. Acute tonsillitis: patients should pay attention to rest, enter a liquid diet and drink more water, through the paste fever patch, warm water scrub and other ways of physical therapy. You can also follow the doctor’s instructions to use antibiotics, such as amoxicillin, azithromycin, etc.; non-steroidal anti-inflammatory drugs, such as ibuprofen, etc. for treatment, to alleviate the symptoms of high fever and so on. 2. Urinary tract infection: When the child has a urinary tract infection, it may also cause high fever and cloudy urine. In the acute stage, bed rest is needed, and children are encouraged to drink more water to increase the amount of urination, and girls should also pay attention to the cleanliness and hygiene of the vulva. Parents can treat the child with physical hypothermia and apply ibuprofen, acetaminophen and other drugs to lower the temperature. If fever and other systemic symptoms are obvious or blood-borne infections, penicillin or cephalosporin drugs are often used for treatment. In addition, acute epidemic encephalitis B, sepsis, leukemia and other diseases may also cause high fever. It is recommended that the patient consult a doctor in time for examination, to clarify the cause of the disease and then carry out targeted treatment, do not use fever-reducing drugs to reduce fever without authorization, so as to avoid delaying the condition. All of the above medications should be used under the guidance of a doctor, avoid self-medication.