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Cold sores: Diagnosis and treatment

Do you get cold sores 6 or more times a year?

To reduce the number of outbreaks, some people who get frequent cold sores take a low dose of antiviral medication every day.

Patient pointing to cold sore on lip

Who should see a dermatologist for a cold sore?

For many people, a cold sore goes away without treatment in 7 to14 days. However, some people need treatment to get rid of cold sores. Dermatologists recommend that you get medical care if you:

  • Have atopic dermatitis (often called eczema)

  • Develop a cold sore near an eye, several cold sores, or lots of pain

  • Have a cold sore that lasts longer than 2 weeks

  • Get cold sores 6 or more times per year

  • Take medication that weakens your immune system, like medication prescribed after an organ transplant or to treat severe psoriasis

  • Have a condition that weakens your immune system, like cancer or HIV

  • Recently received treatment that weakens your immune system, like chemotherapy or a bone marrow transplant

Treatment can help you feel better by healing the cold sores and reducing pain. Treatment can also prevent complications, like a more severe or widespread infection.

How do dermatologists diagnose cold sores?

Your dermatologist can often tell if you have a cold sore by looking at it.

Your dermatologist may also dab a swab, called a culture swab, onto a cold sore to find out if it contains the herpes simplex virus (HSV). This is the virus that causes cold sores.

How do dermatologists treat cold sores?

Your treatment plan may include one or more of the following:

Antiviral medication: Cold sores are caused by a virus, so antiviral medications are used to treat them. Your dermatologist may include one of the following antiviral medications in your treatment plan:

  • Medication you apply directly to the cold sores

    • Acyclovir cream (Brand names: Zovirax cream, Xerese cream)
    • Penciclovir (Brand name: Denavir)
    Sometimes, a cold sore medication that you can buy without a prescription is the right treatment. Your dermatologist knows which medication is the right choice for you.

  • Medication that you take by mouth

    • Acyclovir (Brand names: Sitavig, Zovirax)

    • Valacyclovir (Brand name: Valtrex)

    • Famciclovir (Brand name: Famvir)

Do you have tingling or burning before a cold sore appears?

Treating a cold sore before it appears (or when you first see it) can reduce your discomfort and speed up healing.

How to apply cold sore medication

When applying medication to cold sores, dermatologists recommend gently dabbing the medication on with a clean cotton-tipped swab. This helps prevent the virus that caused the cold sore from getting onto the container and reinfecting you later.

Clean cotton swabs for helping patients apply cold sore medication

Lip balm with SPF 30 or higher: Protecting your lips from the sun can help heal and prevent new blisters. That’s why lip balm with SPF 30 or higher and broad-spectrum protection is often part of a treatment plan.

Sun protection may prevent cold sores

The sun triggers cold sores for some people. Wearing lip balm year-round that has SPF 30 or higher and broad-spectrum protection may help prevent new cold sores.

Woman applying lip balm with SPF 30 to prevent a cold sore

Dermatologists’ tip for preventing reinfection

After your cold sore clears, throw away products like lip balm and lipstick that you used while you had a cold sore. The virus that causes cold sores spreads easily, often contaminating products that you put on or near your lips.

If you use a product contaminated with the virus, you can get another cold sore.

You’ll find more tips that can help prevent another outbreak and tips for at-home treatment at Cold sore remedies dermatologists recommend.

Getty Images

Cohen JI, “Herpes simplex.” In: Kang S, et al. Fitzpatrick’s Dermatology. (ninth edition) McGraw Hill Education, United States of America, 2019:1400-8.

Downing C, Mendoza N, et al. “Human herpesviruses.” In: Bolognia JL, et al. Dermatology. (second edition). Mosby Elsevier, Spain, 2008: 3021-33.

Fatahzadeh M, Schwartz RA. “Human herpes simplex virus infections: Epidemiology, pathogenesis, symptomatology, diagnosis, and management.” J Am Acad Dermatol. 2007;57(5):737-63.

Gopinath D, Koe KH, et al. “A comprehensive overview of epidemiology, pathogenesis, and the management of herpes labialis.” Viruses. 2023 Jan 13;15(1):225.

Leung AKC, Barankin B. “Herpes labialis: An update.” Recent Pat Inflamm Allergy Drug Discov. 2017;11(2):107-13. 

Worrall G. “Herpes labialis.” BMJ Clin Evid. 2009 Sep 23;2009:1704.

Written by:
Paula Ludmann, MS

Reviewed by:
Elisa Gallo, MD, FAAD
Laurel Geraghty, MD, FAAD
Shari Lipner, MD, PhD, FAAD
Sanna Ronkainen, MD, FAAD

Last updated: 2/1/24