Generally speaking, influenza is most serious after the incubation period, that is, the first three days of symptoms, but the specific situation varies from person to person. Under normal circumstances, the incubation period of influenza is usually 1~7 days, mostly 2~4 days, during which there are no obvious symptoms, and some people with strong body resistance may recover on their own. After the incubation period, it is likely to appear more obvious symptoms, such as headache, fatigue, fever, muscle pain, nausea and vomiting, etc., the degree of its severity and personal health also has a certain relationship, if their own physical health is better, the relevant symptoms will not be particularly serious. If you are in good health, the symptoms will not be particularly serious. You need to consult a doctor in a timely manner for treatment and control of the disease, and pay attention to self-isolation so as not to infect other people.