A swollen lip may be the result of an infection in the patient’s lip, especially a bacterial infection resulting in local inflammatory edema, which may be accompanied by significant pain. It may also be a viral infection in the area, such as a herpes simplex virus infection, which forms a distinct inflammatory reaction that over time may result in erythema and blisters on top of the erythema, and the blisters are mostly clustered and the patient mostly has significant pain. There is also a case of angioneurotic edema in the area, also called giant urticaria, which is a special type of urticaria caused by allergic factors, and the patient mostly presents with local edema and a certain degree of numbness.