Mouth ulcer - Complications 

Mouth ulcers rarely cause any complications. Over time, most mouth ulcers will heal naturally. Those that do not can usually be treated with medication.

A mouth ulcer may indicate an underlying health condition, but the ulcer itself will not be the cause of any illness.

Bacterial infection

The only complication mouth ulcers can cause is a bacterial infection. However, this is very rare. In some cases, an infected ulcer can cause the bacteria to spread to other areas of your mouth, such as your teeth. If your ulcer becomes infected, you might need treatment with antibiotics.