Please consult with your medical professional about the applicability of this information to your own situation. The content below includes links to external sites, which will open in a new browser window.

What causes cold sores?

The herpes simplex virus causes cold sores. While there are eight types of herpes viruses, it is mostly type 1 and occasionally type 2 that cause cold sores, which are also known as fever blisters, oral herpes, or herpes labialis. Recurrent cold sores are usually caused by the type 1 virus.

Why do some people get cold sores so frequently?

The majority of people are exposed to the type 1 herpes simplex virus by direct contact with someone with cold sores before they are 10 years old. Most will develop a mild case of one or two cold sores. Some will have a more severe infection called “gingivostomatitis” that is characterized by dozens of painful cold sores on the tongue, gums and lips, and often is accompanied by fever and sore throat. In severe cases of gingivostomatitis, children are hospitalized because of dehydration.

After the initial infection, whether mild or severe, the herpes virus that causes cold sores remains dormant, or latent, in the nerve root connected to the lips. Essentially, the virus “hides and waits.” Unrelated to the severity of the first episode of cold sores, and for unknown reasons, about 25% of exposed individuals will go on to have recurrent cold sores for the rest of their lives. Generally, the virus will be reactivated and cause cold sores as a response to stress, tiredness, illness, sunlight, fever, diet, menstruation or pregnancy. The frequency of outbreaks decreases after age 35.

What cold sore treatments are available?

There is no available cure for recurrent cold sores. Treatments that decrease pain and speed healing include the topical creams acyclovir (Zovirax®), docosanol (Abreva®) or penciclovir (Denavir®). Oral medications include oral acyclovir (Zovirax®), oral famciclovir (Famvir®), and oral valacyclovir (Valtrex®).

What new cold sore treatments are being studied?

New antiviral medications are being developed, as are new routes of administration of existing medications. In one study conducted at Rochester Clinical Research, the medication acyclovir (Zovirax®) was administered in a tablet that adheres to the patient’s upper gum and gets slowly absorbed, targeting the release of the medication to the area of the body affected by the herpes simplex virus.

For information on the herpes simplex virus:

Wikipedia: Herpes simplex

For more information on cold sores: Cold Sores Cold Sores