There's a blister inside the mouth that has persisted for over a year without disappearing.

A mouth blister that has persisted for over a year may be caused by physiological factors, or could result from pathological conditions such as vitamin deficiency or oral ulcers.

I. Physiological Causes

If a patient frequently consumes spicy and irritating foods—such as chili peppers, garlic, or raw onions—prolonged irritation from these foods may lead to small blisters in the mouth. If there are no significant discomfort symptoms, special treatment may not be necessary. Adjusting the diet by avoiding spicy and irritating foods and increasing intake of fresh fruits and vegetables can help promote recovery.

II. Pathological Causes

1. Vitamin B Deficiency

Excessive eating, poor dietary habits, or frequent late nights may lead to gastrointestinal dysfunction and poor nutrient absorption, resulting in vitamin B deficiency. Patients may experience symptoms such as dry skin, oral mucosal erosion, insomnia, diarrhea, and anemia. Treatment may include taking compound vitamin B tablets as directed by a physician.

2. Oral Mucosal Erosion

This is usually caused by improper diet, reduced immunity, or bacterial infection. When immunity is severely compromised, bacteria can proliferate locally and irritate the oral mucosa, leading to mucosal damage, small blisters, painful eating, and erosion. As prescribed by a doctor, medications such as cefuroxime axetil tablets, ribavirin tablets, or Shuanghuanglian oral liquid may be used for treatment.

In addition to the above causes, persistent blisters may also be due to conditions such as oral herpes. It is important to maintain good oral hygiene in daily life to prevent local bacterial proliferation, inflammation, and the development of oral diseases.