Mouth ulcers on the gums are usually small, painful sores caused by irritation, minor injury, or underlying health factors such as stress or vitamin deficiency. Most are harmless and heal on their own within 1–2 weeks, but frequent or non‑healing ulcers can signal a medical issue that needs checking.

Main causes on the gums

  • Minor trauma to gums :
    • Brushing too hard or using a hard toothbrush.
    • Scratches from sharp foods (chips, toast), hot drinks, or dental work like braces, dentures, or rough fillings.
  • Nutritional deficiencies:
    • Low vitamin B12, iron, folate, or other B vitamins can make gum tissue more fragile and prone to ulcers.
  • Stress, fatigue, and hormones:
    • Emotional stress, poor sleep, or hormonal shifts (for example, menstruation or pregnancy) can trigger or worsen mouth ulcers.

Less obvious medical triggers

  • Immune and gut conditions:
    • Crohn’s disease, coeliac disease, Behçet’s disease, and other autoimmune or inflammatory conditions can cause recurrent gum ulcers.
  • Infections:
    • Viral (such as herpes simplex), bacterial, or fungal infections like oral thrush may present as painful sores or patches on the gums.
  • Medicines and treatments:
    • Some anti‑inflammatories, beta‑blockers, chemotherapy drugs and other medications list mouth ulcers as a side effect.

Everyday irritants and sensitivities

  • Food and product sensitivity:
    • Citrus fruits, spicy foods, chocolate, coffee, nuts, gluten, or toothpaste ingredients like sodium lauryl sulfate can irritate gum tissue in some people.
  • Tobacco and quitting smoking:
    • Smoking and other tobacco products can irritate the mouth, and some people briefly get more ulcers when they stop smoking as the mouth environment changes.

When to worry

  • Warning signs that need urgent dental or medical review include:
    • A gum ulcer that lasts longer than 2–3 weeks, keeps growing, or is very hard or painless.
    • Recurrent ulcers with weight loss, fevers, severe diarrhea, or difficulty swallowing, which can point to systemic disease or, rarely, mouth cancer.

Simple steps that can help

  • Use a soft toothbrush, avoid known trigger foods, and keep up gentle but thorough oral hygiene to reduce irritation on the gums.
  • Over‑the‑counter gels, mouth rinses, and avoiding heat/spice/acidity can ease pain while the ulcer heals, but persistent or frequent gum ulcers should be assessed by a dentist or doctor to rule out deficiencies, infections, or other conditions.

Information gathered from public forums or data available on the internet and portrayed here.