Mouth Ulcers (Canker Sores)

A single ulcer can follow cheek biting, a sharp tooth, rough filling, braces, poorly fitting dentures, a burn from food or drink, or a toothbrush injury. Stress, hormonal change, vitamin deficiency and some medicines can also be triggers.

Many mouth sores settle in 10 to 14 days without treatment, though some last as long as six weeks. Cold sores may start with tingling, burning or tenderness, then form blisters and crust.

Several ulcers can occur with hand, foot and mouth disease, oral lichen planus, Crohn's disease, coeliac disease or a weakened immune system. Less commonly, mouth sores can signal illness, a tumour or a medicine reaction.

Assessment includes a close check of the mouth and tongue alongside questions about symptoms and medical history. Location, appearance and possible irritants help distinguish canker sores, cold sores and other mouth lesions.

Pain relief can include a numbing medicine, a steroid gel, a paste that reduces swelling or a chlorhexidine mouthwash. Severe, persistent or infected ulcers may be treated with stronger prescribed medicine.

Avoid hot drinks, spicy or salty foods and citrus when a sore is painful. Cool water, salt-water gargles and ice pops can make a mouth sore more comfortable.

An ulcer lasting longer than three weeks, becoming bigger, bleeding, growing more painful and red, or occurring with skin or genital ulcers or painful swollen joints needs assessment. A long-lasting ulcer can sometimes be a sign of mouth cancer.

Chew slowly, use a soft-bristle toothbrush and avoid very hot food or drink. Address sharp or broken teeth and poorly fitting dentures, since they can repeatedly irritate the mouth.