Mouth ulcers are small, very sore patches inside your mouth. Nearly everyone gets them at some time. Most go away in a week or so. But some people keep getting them. There are lots of mouthwashes, gels, and creams that may make your mouth ulcers go away faster and hurt less.
We've brought together the best research about mouth ulcers and weighed up the evidence about how to treat them. You can use our information to talk to your doctor and decide which treatments are best for you. This information is for people who keep getting mouth ulcers.
Mouth ulcers are small, white sores inside your mouth where the top layer of the skin is damaged. They are very sore but usually don't last long.
If you keep getting bouts of mouth ulcers every few months, weeks, or even every few days, doctors say you have recurrent mouth ulcers.  You may also hear them called aphthous ulcers.
Doctors divide recurrent mouth ulcers into three main types, depending on how big they are and where in your mouth you get them.Minor mouth ulcers
Most people get minor mouth ulcers. These are round or oval, and usually less than 5 millimetres (a little less than one-fifth of an inch) across. They tend to be greyish-white, with redness around them, and are usually on the inside of your lips or cheeks, or on the floor of your mouth. People usually get one to five ulcers at a time. Major mouth ulcers
Major mouth ulcers are less common than minor mouth ulcers, and they are oval and larger. They may be 1 to 3 centimetres (nearly one-half to one-and-a-quarter inches) across. They often happen on the lips or towards the back of the roof of your mouth (the soft palate), but they can be anywhere in your mouth. People usually get one to 10 ulcers at a time. Herpetiform ulcers
Some people get lots of small, painful ulcers called herpetiform ulcers. These ulcers can occur anywhere in the mouth. You may have as many as 100 at a time, each measuring 2 to 3 millimetres (about one-eighth of an inch) across. Some join together to form large, irregularly-shaped ulcers. 
For references related to Mouth ulcers click here