Cold Sores (Nongenital Herpes Simplex Infections)

  • Medical Author:

    Sandra Gonzalez Gompf, MD, FACP is a U.S. board-certified Infectious Disease subspecialist. Dr. Gompf received a Bachelor of Science from the University of Miami, and a Medical Degree from the University of South Florida. Dr. Gompf completed residency training in Internal Medicine at the University of South Florida followed by subspecialty fellowship training there in Infectious Diseases under the directorship of Dr. John T. Sinnott, IV.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Cold Sores Slideshow

What tests do health-care professionals use to diagnose oral herpes?

The diagnosis of herpes (cold sores) is easily made based on the visual appearance of the lesions, and the best approach is to see a doctor at the first sign of a blister. If there is concern that the rash may not be herpes, a swab of blister fluid may be collected for viral culture or polymerase chain reaction (PCR) test. This is most useful in the first 48 hours before the blister has crusted over. If lesions resolve, then cultures are of no help, because there's nothing left to culture. Culture results take a minimum of three to five days.

PCR testing detects herpes DNA, but it is not as readily available as culture and is a very expensive test to do for simple cold sores.

Blood tests for herpes antibodies are not usually needed, since finding antibodies to herpes just means that the body has been exposed to this virus at some point in the past. It does not determine if the current lesion is due to herpes. They can be done, though, if the diagnosis is unclear or there is a specific reason to know for certain.

How long do cold sores last?

In primary herpes, the healing process usually takes two to three weeks, but skin pain can last for one to six weeks.

Medically Reviewed by a Doctor on 6/15/2016

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