Hydrogen Peroxide & Cold Sores

Cold sores are small, painful blisters that appear on the lip or around the mouth. Also called fever blisters, these sores are caused by the herpes simplex virus (HSV). Although antiviral medications and pain relievers are standard treatments for this infection, hydrogen peroxide is a common home remedy that if used early, may dry the sores and speed healing.

Hydrogen peroxide can help dry a cold sore. Credit: belchonock/iStock/GettyImages

Cold Sore Basics

More than half of Americans under the age of 50 are HSV carriers and as a result, experience rare to frequent cold sore outbreaks. Cold sore sufferers can usually tell an eruption is eminent when the lips start to itch and tingle. Shortly after these symptoms start, fluid-filled blisters appear. These will ultimately burst, ooze fluid and finally scab over. Cold sores are very contagious during this time, and are spread by direct contact.

Home Measures

Self-care strategies can help reduce cold sore pain, dry the sore and hasten healing time. For example, using a cold compress on the lip, taking pain relievers such as acetaminophen or ibuprofen, or applying lidocaine-based numbing agents can help manage pain. Some home measures, such as dabbing hydrogen peroxide on the affected area in the early stages of an outbreak, may dry the blisters and potentially speed healing. Hydrogen peroxide is considered a mild antiseptic, which can help clean the affected area and reduce the risk of infection.

Hydrogen Peroxide Safety

Just how well hydrogen peroxide works to reduce pain and speed healing is unclear, because of a lack of published, quality research on this treatment. But if you want to try it, take care to ensure safety. Consumers usually purchase hydrogen peroxide in a 3 percent concentration, which can be applied at full strength or diluted with one part water, if irritation occurs. Care should be taken to avoid direct application of concentrations above 3 percent, since 10 percent solutions can be corrosive, and the higher industrial concentrations can be highly toxic.

Antiviral Medications

Although home remedies are often used for cold sores, antiviral creams and pills are the standard of care. These antivirals can relieve discomfort and shorten healing time, and are most effective when taken at the first sign of a cold sore -- when the tingling or pain starts but before the blisters appear. Most antivirals are available only by prescription, but docosol (Abreva) is an example of an over-the-counter cold sore treatment.


If you suffer from frequent or severe cold sores, take care to avoid touching the sores and wash your hands regularly to ensure you do not pass this virus on to others. Also, talk to your doctor about antiviral creams or pills so that you can minimize the severity of your cold sore outbreaks.

Reviewed by Kay Peck, MPH RD

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