Mouth ulcers are usually small, painful sores or lesions that develop on the soft lining of the mouth. Anyone can get mouth ulcers and they are usually harmless. Mouth ulcers are painful, non-contagious sores in the mouth that usually heal in 1–2 weeks but can make eating, drinking, or speaking uncomfortable. Learn more. Soothe painful mouth ulcers naturally with simple home remedies like saltwater, honey, and coconut oil. Quick relief, easy to try at home. Understand your oral ulcer symptoms with Buoy, including 9 causes and common questions concerning your oral ulcer.