1, physiological reasons, 4-6 pm or exercise, hot bath, full meal, female ovulation and pregnancy, the body temperature may increase slightly, but generally does not exceed 37.5℃;
2, pathological fever, including infectious and non-infectious, infectious fever is more common, such as tuberculosis, low fever in the afternoon, accompanied by fatigue, night sweats, loss of appetite, emaciation and so on. , can also be seen in AIDS, there can be long-term low fever, other non-infectious reasons, such as internal bleeding, hyperthyroidism, rheumatic fever, some drugs can also cause drug fever, can also be seen in trauma, surgery, these reasons can also cause low fever.