Mouth ulcers, which are also known as canker sores, are pleasant little sores that appear in your mouth and cause all kinds of irritation until they’re gone.

They’re usually harmless and aren’t contagious, but they can be seriously irritating and painful while you wait for them to heal.

Mouth ulcers appear on the insides of your mouth or lips, on your gums, or on your tongue and they look like little round white, yellow, or grey sores.

You’ll usually remember that your mouth ulcer is there when you try to eat, drink, talk, or brush your teeth and annoy that little sore, causing a pain that makes you want to give up on using your mouth altogether until it’s healed.

There are lots of reasons why you may have a mouth ulcer, and luckily a lot of them are preventable, including:

• Biting the inside of the cheek
• Badly fitted braces or dentures
• Rough fillings
• A sharp tooth
• Cuts or burns when eating and drinking
• Damaging your gums while brushing your teeth
• Feeling stressed, anxious, or tired

However, sometimes mouth ulcers just can't be prevented, so you'll just need to let them heal and move on.

Some causes of mouth ulcers that can't be prevented include:

• Hormonal changes
• A genetic history of getting mouth ulcers more often
• A long-term condition, such as inflammatory bowel disease, coeliac disease, or Behçet's disease
• A vitamin B12 or iron deficiency
• Some types of medication
• Stopping smoking
• Allergies

Mouth ulcers usually go away by themselves after a week or so, so you’ll need to take care to keep from aggravating the area until then.

We’d recommend avoiding spicy, rough, or very hot or cold foods until your mouth ulcer has passed.