Acute nephritis can also cause facial swelling in patients. The pathological damage in patients with acute nephritis is the diffuse proliferation of glomerular cells, which reduces the glomeruli's ability to filter blood. As a result, patients may experience proteinuria and hematuria. Decreased kidney function in water excretion can lead to water accumulation in the body, causing edema in the lower limbs or facial area. The increase in urinary protein can also increase vascular permeability and decrease plasma osmotic pressure, leading to the movement of water outside the blood vessels. These factors can all cause edema. In the body, water tends to accumulate in areas where tissues are looser, such as the facial area. Thus, it is possible for patients with acute nephritis to experience facial swelling.