There is no unified statement on how many days hives will occur, as follows: 1. Immediate recovery from allergens: Some people may have transient hives that develop suddenly, but after treatment the rash subsides and no longer starts. This is usually triggered by sudden exposure to an allergenic substance. 2. 1-2 weeks: Some hives are triggered by infection, and this type of hives may last 1-2 weeks, or even longer. 3. months to years: Chronic hives may recur for months to years, usually associated with various chronic diseases, including chronic The recurring episodes of chronic hives can be triggered by gastroenteritis, cholecystitis or thyroid disease. Therefore, the exact number of days that hives will occur depends largely on what causes the hives. Patients with acute allergies usually recover in a short time, while hives caused by chronic conditions can often take months to years to recover.