Oral Herpes (Cold Sores): Symptoms & Signs

Medically Reviewed on 9/22/2020

Oral herpes refers to an infection of the tissues around the mouth with one of the two herpesviruses, herpes simplex virus 1 or 2. It is a very common infection that produces the characteristic cold sore or fever blister. The virus resides deep in the nerve roots and may reactivate at a later time, causing the same symptoms and signs in the same location. Oral herpes is also referred to as herpes labialis.

Signs and symptoms of HSV-1 infection include painful, sore lips with tiny fluid-filled lesions (blisters), ulcers, and redness. Other associated symptoms include tingling or burning pain in the lips. Symptoms go away within 1-2 weeks but often reoccur throughout life due to reactivation of the virus.

Cause of oral herpes (cold sores or fever blisters)

Herpes simplex virus type 1 (HSV-1) is the most common cause of oral herpes.

Other oral herpes (cold sores) symptoms and signs

  • Painful, Sore Lips
  • Skin Redness
  • Tiny Fluid-Filled Lesions (Blisters)
  • Ulcers Inside the Mouth


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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.