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Cold sores: Diagnosis and treatment

How do dermatologists diagnose cold sores?

A dermatologist can often diagnose a cold sore by looking at it.

Your dermatologist may also swab a cold sore. Fluid from the sore can be examined to find out if you have a herpes virus called the herpes simplex virus (HSV). This is the virus that causes cold sores.

How do dermatologists treat cold sores?

To treat cold sores, a dermatologist may prescribe:

Antiviral medication: Cold sores are caused by a virus, so antiviral medications are used to treat them. Your dermatologist may prescribe medication that you:

  • Apply directly to the sores, such as docosanol cream or acyclovir cream

  • Take by mouth, such as acyclovir, valacyclovir, or famciclovir

For someone who has a serious outbreak and cannot get relief from the above, a dermatologist may prescribe an antiviral medication that you receive through an IV, such as foscarnet or cidofovir. You’ll be closely watched if one of these medications is necessary.

If you get cold sores often and have a weak immune system, your dermatologist may prescribe a prescription cream called penciclovir. It can reduce the time that you have cold sores. To work, you need to apply it to the skin with the first symptoms of a cold sore, such as burning or tingling.

Treatment tip

When applying medicine to cold sores, dermatologists recommend gently dabbing the medicine on with a clean cotton-tipped swab.

Use a clean cotton swab to apply medicine to cold sores

Pain medication: If you have a lot of pain, your dermatologist may prescribe a medication that you apply to the sores, such as lidocaine.

Sunscreen: While the sores are healing, it’s important to protect them from the sun. A lip balm with an SPF of 30 or higher and broad-spectrum protection can help protect your lips. Worn year round, this lip balm may help prevent new cold sores.

Treating cold sores has benefits. Treatment can shorten your outbreak. It may even prevent you from getting a cold sore if you start treatment at the first sign of a cold sore (a tingling or burning sensation on your skin).

Treatment can also reduce your risk of spreading the virus to others.

Treatment is highly recommended if you get a cold sore and have:

  • Atopic dermatitis (usually begins in childhood and is often called eczema)

  • Sores near your eyes

  • A lot of cold sores

  • A lot of pain

  • Sores that spread to another part of your body, such as your hands or genitals

  • HIV, AIDS, cancer, or another disease that weakens your immune system

  • Cancer and are getting chemotherapy

  • To take medication that suppresses your immune system, such as medicine to control severe psoriasis or prevent organ rejection

  • Cold sores frequently

  • An outbreak that lasts more than two weeks

It’s important to treat cold sores if you have any of the above because the cold sores may not go away without treatment. Left untreated, the virus that causes cold sores can spread to other parts of your body. Some people develop another illness and become very sick.

If you’re healthy, you can treat cold sores on your own. Find out what dermatologists recommend at, Cold sores: Self-care.

Young man with cold sore on lip

What is the outcome for someone who has cold sores?

Cold sores cannot be cured. Some people get the virus and have just one outbreak. Others continue to get cold sores.

If you get cold sores several times a year, tell your dermatologist. A prescription antiviral medicine may help. Taking this medicine at the start of a cold-sore outbreak can shorten the amount of time you have cold sores. Some people who get cold sores frequently take this medicine every day. Taken daily, it can help prevent outbreaks of cold sores.

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