A mouth ulcer that wont heal could be serious., Most ulcers are harmless, but persistent ones may signal oral cancer symptoms. Early detection ensures simpler treatment, faster recovery, and better Flying With Your Vape OB Vape Travelling with E Cigarettes & Vapes Abroad Tablites She Thought Her Mouth Sores Were Just Ulcers. Now She's Having Her Tongue Removed AOL Dentistry Vaping & your mouth: what you might notice at home If you vape, watch out for: Bleeding when brushing or flossing Persistent bad breath Tooth sensitivity Mouth Ulcers UF Health