Mouth sores are one of those oral health problems that almost everyone experiences at some point and almost no one fully understands. Canker sores get confused with cold sores; some lesions that seem minor need professional evaluation; some that seem alarming are entirely benign.
Canker sores (aphthous ulcers)
The most common type of mouth sore. They appear on soft tissues inside the mouth — inner lips, cheeks, tongue, floor of mouth, soft palate — never on the outer lip or hard surfaces. Round or oval, with a white or yellowish center surrounded by a red border. Painful out of proportion to their size. Not contagious. Not caused by herpesvirus. Cause is incompletely understood — likely involving immune dysregulation, with triggers including stress, trauma (biting the cheek), sodium lauryl sulfate in some toothpastes (SLS-free toothpastes may help recurrent sufferers), hormonal changes, and nutritional deficiencies. Nutritional connections worth knowing: vitamin B12 deficiency, folate deficiency, iron deficiency, and zinc deficiency have all been associated with recurrent aphthous ulcers. Some people with recurrent canker sores improve dramatically with B12 supplementation. Most resolve on their own in 7-10 days. Topical corticosteroids reduce pain and healing time.
Cold sores (herpes labialis)
Caused by herpes simplex virus type 1 (HSV-1) and appear on the outer lips and at the lip border — never inside the mouth on soft tissue. They begin as tingling, then develop fluid-filled blisters that burst and crust over. Highly contagious during active outbreaks. Once infected, the virus remains latent in nerve ganglia and reactivates with triggers: sun exposure, stress, illness, immune suppression, hormonal changes. Antiviral medications (acyclovir, valacyclovir) reduce severity and duration when started during the prodromal phase.
White patches: which ones need attention
Oral thrush — white patches that wipe off — is a fungal infection needing antifungal treatment. More common with antibiotic use, inhaled corticosteroids, immunosuppression, or diabetes. Some interest has emerged in oral probiotics for oral candidiasis — L. paracasei specifically has shown ability to inhibit Candida colonization in the oral cavity; this strain appears in both ProDentim and GumAktiv. Leukoplakia — white patches that cannot be wiped off — needs professional evaluation and possible biopsy. Most are benign; some are dysplastic (premalignant). Any oral lesion that hasn’t resolved within 2 weeks should be evaluated by a dentist or doctor. Early detection of oral cancer dramatically improves outcomes.
Educational content. Persistent or unusual oral lesions require professional evaluation.
