Are cold sores typically caused by Herpes Simplex Virus (HSV) type 1 or type 2?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: April 20, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Cold sores are usually caused by herpes simplex virus type 1 (HSV-1), not type 2.

Key Points

  • HSV-1 typically affects the mouth area, causing painful blisters or sores on the lips, gums, or around the mouth 1.
  • HSV-2, by contrast, most commonly causes genital herpes, although it can also cause oropharyngeal infection and herpes labialis 1.
  • The primary cause of herpes labialis is HSV-1, and at least 50% of new cases of herpes genitalis in developed countries are now caused by HSV-1 1.
  • About 80% of cold sores are caused by HSV-1, which spreads through direct contact with infected sores or bodily fluids and remains dormant in nerve cells between outbreaks.
  • Triggers for cold sore recurrence include stress, illness, sun exposure, hormonal changes, and weakened immunity.
  • Common treatments include antiviral medications like acyclovir (Zovirax), valacyclovir (Valtrex), or famciclovir (Famvir), which work best when started at the first sign of an outbreak 1.
  • Over-the-counter creams containing docosanol (Abreva) may also help reduce healing time.

Treatment and Prevention

  • The aim of antiviral therapy is to block viral replication to enable shortening the duration of symptoms and accelerate the resolution of lesions 1.
  • Two categories of antivirals are available for treatment of herpes labialis: topical and oral therapies 1.
  • It is imperative that therapy is initiated as soon as possible to ensure an optimal therapeutic beneficial effect 1.

From the Research

Herpes Simplex Virus Types

  • Herpes Simplex Virus (HSV) has two main types: HSV-1 and HSV-2 2
  • HSV-1 is commonly associated with oral herpes, which can cause cold sores on the lips, tongue, or mouth 2, 3
  • HSV-2 is primarily associated with genital herpes, but it can also cause oral herpes 2, 3

Cold Sores and Herpes Type

  • Cold sores are usually caused by HSV-1, not HSV-2 2, 3
  • HSV-1 is the primary cause of herpes labialis, which is characterized by the appearance of cold sores on the skin, lips, tongue, or buccal mucosa 2, 3

Treatment of Herpes Simplex Infections

  • Antiviral medications such as acyclovir, valacyclovir, and famciclovir are commonly used to treat herpes simplex infections 4, 2, 3, 5, 6
  • These medications can help reduce the severity and duration of symptoms, but they cannot completely eradicate the virus from the body 2, 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Acyclovir in the Treatment of Herpes Viruses - A Review.

Current medicinal chemistry, 2020

Research

Pharmacology of new antiherpes agents: famciclovir and valacyclovir.

Journal of the American Pharmaceutical Association (Washington, D.C. : 1996), 1997

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.