Question: what are sores on lips?
Answer: Lip sores (ulcers) have various causes. A lip sore with hard edges may be a form of skin cancer (see Types of Oral Cancer; see also Lips and Sun Damage). Sores may also develop as a symptom of other medical conditions, such as erythema multiforme, recurrent oral herpes simplex virus infection (cold sores), or syphilis.