IgA nephropathy is a chronic glomerulonephritis with varying degrees of severity and diverse clinical manifestations. Whether patients can eat watermelon depends on their kidney function and the presence of edema symptoms. If patients have kidney failure and noticeable edema, it is advised that they avoid eating watermelon, as it contains a significant amount of potassium ions. Consuming watermelon may lead to hyperkalemia due to the intake of large amounts of potassium ions. The main component of watermelon is water, and if patients have noticeable symptoms of edema, eating watermelon may exacerbate these symptoms and even cause issues like hypertension. If patients do not have noticeable edema and their kidney function is normal, eating small amounts of watermelon should not be a major concern.