The sudden swelling of the upper lip may be caused by the following reasons: First, allergy of the lips, it is due to the contact of the upper lip with suspected allergenic drugs, food or cosmetics, resulting in angioneurotic edema on the lips, causing rapid swelling and tightness of the upper lip in a short period of time. The local trauma of the upper lip, because the tissue at the lip is very loose and rich in blood flow, once the trauma occurs, it will lead to the swelling of the lip very obviously. If there are more ulcers or the ulcer surface is deep and large, it will also cause the upper lip to swell. It is caused by the lack of vitamins and trace elements in the body. Patients with chronic lip inflammation will lead to dry, cracked and flaky lips, and patients with prolonged symptoms will have swollen and thickened lips.