The symptoms of the rash from allergic purpura generally subside naturally after about 7 to 10 days. However, if care is not taken in daily life, there is a high likelihood of recurrence of the rash. Patients with allergic purpura should avoid vigorous activities such as fast running and should also avoid getting chilled and infections, as both cold and infections could exacerbate the condition. Additionally, patients should consume less of foods like shrimp and crab, which may trigger allergic reactions.