Fever subsides during the day and develops at night for three consecutive nights, which is considered to be related to oral antipyretics, insufficient frequency of medication and tuberculosis infection. 1. Oral antipyretics: in some patients with high fever, after taking oral antipyretics, the effect of the drug can last for 6-8 hours, and the temperature can be effectively controlled during the daytime, and the patient can have high fever again after the effect of the drug at night. 2. Drug frequency is not enough: bacterial infections should be selected according to the characteristics of the drug antimicrobial therapy, such as quinolone drugs levofloxacin can be selected once a day static; cephalosporins, such as cefoperazone, cefuroxime, etc., should be static 2-3 times a day. The blood concentration or duration of the drug is not enough to achieve the purpose of treatment. 3. Tuberculosis infection: when tuberculosis infection occurs there will be symptoms such as afternoon hot flashes, night sweats and weakness. After the onset of this disease, anti-tuberculosis treatment should be carried out under the guidance of specialists, and the representative drugs include rifampicin, isoniazid, ethambutol and so on. Fever subsides during the day and three consecutive fevers in the evening should be consulted in the hospital to avoid aggravation of the disease and increase the difficulty of treatment.