Cold sores are small, painful, fluid-filled blisters that usually occur in clusters on or around the lips. Sometimes called fever blisters, cold sores are caused by the herpes simplex virus. There are two strains of herpes simplex virus that cause cold sores: HSV-1 and HSV-2. HSV-1 is more commonly linked with cold sores (oral herpes), while HSV-2 is more often the cause of genital herpes. It is important to note that you can contract HSV-1 and HSV-2 in either location (oral or genital). Approximately 80 percent of cold sore cases are caused by HSV-1, while the remaining 20 percent are caused by HSV-2.
Oral herpes can be transmitted by kissing, sharing eating utensils or drinks, or during sex. Since oral herpes can be contracted from both Type 1 and Type 2 strains of the Herpes Simplex Virus, our doctors recommend getting tested for both of these HSV strains at the same time.
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These uncomfortable sores often appear in small clusters. They can best be identified by their irritated, reddish or pinkish color, Cold sores have been referred to as “weepy” because once the blisters break, they will leak fluids and then eventually scab over.
Cold sores most commonly appear on or around the lips, however, sometimes HSV-1 and HSV-2 can spread to the fingertips (called herpes whitlow), the eyes (called ocular herpes), or widespread areas of the skin (people with eczema are more susceptible to this).
Sores caused by HSV are contracted through skin-to-skin contact with someone whose blisters are present. Additionally, you can still receive a cold sore from someone whose blisters are not present by sharing bodily fluids. This means that though there is no outbreak, you may not be entirely in the clear. This can occur in a number of ways, including kissing and oral sex, or sharing toothbrushes, food utensils, razors, and towels.
Cold sores are extremely contagious, so much so, that about two-thirds of the world’s population has HSV-1. Additionally, 1 in every 6 people has HSV-2. If you have cold sores, it is important to be aware and avoid skin-to-skin contact with small children and those with a weak immune system.
The first outbreak of cold sores will typically be the worst, and may include:
After the first outbreak symptoms will often be reduced, but may still include:
Cold sores can best be treated with suppressive therapy, using an oral antiviral medicine such as acyclovir, famciclovir, or valaciclovir. These medications must be prescribed by a doctor. They are used to help to reduce the severity and frequency of symptoms. However, they cannot cure the infection. Cold sores are a symptom of herpes (or the herpes simplex virus), and there is currently no cure.
It’s important to get tested for both HSV-1 and HSV-2 because physically, they are almost identical. STDcheck.com offers a package to test for both strands of the virus.The technicians in our CLIA-certified labs take a small blood sample to conduct the test. No undressing or uncomfortable swabbing is necessary.
If the test returns as positive, you can call and schedule a phone consultation with one of our physicians. At their discretion, they may prescribe treatment. Call our Care Advisors to schedule a consultation at 1-800-456-2323.
Medically Reviewed by William Terranova, MD on June 9, 2023Written by Lauren Crain on June 20, 2018