Valentine's Day can be a particularly sensitive time. Many of those because it was too painful, but also because they thought you could catch a mouth ulcer from someone who has them - which of course is not true. The same Gallop survey confirmed how mouth ulcers make it difficult to eat, drink, and even talk. A large number of people with mouth ulcers don't want to socialise either. There are two common causes of mouth ulcers.
Accidental damage is responsible for many.
These last for a week or more unless the damage continues happening, in which case they will not disappear until the cause, e.g. a rough tooth, is treated. The other common type are called aphthous ulcers and these appear when someone's feeling stressed, or under the weather. Puberty is often when they appear for the first time and they can run in families. These aphthous mouth ulcers can take a couple of weeks to heal and more are likely to keep appearing until someone's feeling relaxed and well again. Other more serious causes of mouth ulcers include herpes infection, inflammatory bowel disease, and immune disorders, but these are usually accompanied by other symptoms around the body.