The NHS says that mouth ulcers are common, and most of them are harmless.But sometimes, they say, ulcers ― small, usually circular sores that form on the inside of your lip, inner cheek, or gums ― need to be investigated. Speaking to HuffPost UK, Neil Sikka, Director of Dentistry for Bupa Dental Care said: “There are a few signs and symptoms of mouth cancer that patients should look out for.“These generally include mouth ulcers that don’t heal after a 2-3 week period, or unexplained lumps both in the mouth and swollen lymph glands in the neck.”What are the signs of mouth cancer and how do I check for it? Aside from ulcers that take ages to heal and unexplained lumps in your neck or mouth, Dr Sikka adds: “Other symptoms may include difficulty in swallowing which lasts for a few weeks, red or white patches in the mouth, teeth becoming loose for any unexplained reason, or unexplained bleeding or numbness in the mouth.“It’s important to remember that all these signs and symptoms can also havea normal explanation, but if they concern you or are persistent then you should visit your dentist for a professional check-up,” the expert added. As with all cancers, the earlier it’s spotted, the better.