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Cold sores

Also known as: Fever blisters, Oral herpes

Cold sores symptom guide: what it can mean, possible causes, and when to seek care. Educational only.

Overview

Cold sores are often caused by herpes simplex virus and may return during stress or illness. They differ from inside-mouth ulcers. Avoid touching and sharing utensils while sores are active.

Possible causes

  • Herpes simplex virus
  • Stress or fatigue
  • Strong sun
  • Fever or infection
  • Temporarily lowered immunity

When to see a doctor

Visit a clinic if sores are severe, spread toward the eye, or keep returning often.

Related conditions