What is the cause if a patient develops a lesion on the lower lip the next day?

• A. Bit lip
• B. Cold sore
• C. Herpes simplex
• D. Allergic reaction

Answer: (A)

The likely cause is self-inflicted trauma from lip biting while the lip is numb after local anesthesia. When a patient can’t feel the lip, they may accidentally bite or clench the tissue, which can create a lesion that appears the next day as a small ulcer or raw patch. This is a mechanical, traumatic injury rather than an infectious or allergic process.

Cold sores caused by herpes simplex virus present differently: they typically start with a tingling sensation or prodrome, then form vesicles on an erythematous base and crust over several days, not usually tied to a recent numbness or dental visit. An allergic reaction would usually show rapid swelling, redness, itching, or hives rather than a single localized lip lesion arising specifically after numbness.