Peppermint oil acts as a natural treatment for cold sores because it slows down the progress of the herpes simplex virus which is what causes the sores to form. Consequently, it prevents your cold sore from becoming any larger. Many people find that applying a small dab of peppermint oil to a cold sore minimizes sensitivity and eases their discomfort. A research study at the University of Heidelberg demonstrated that peppermint oil was able to penetrate the skin and have an antiviral effect on the herpes simplex virus.
Put a few drops on a cotton swab and press it against your cold sore for about 30 seconds to a minute. Your lip will feel refreshed, free of pain, and nice smelling too. It also appears to have the effect of making the cold sore shrink a bit, although only temporarily.
You do need to be cautious when you’re using peppermint oil though, because an excessive amount of it can be unsafe, even though it’s a natural treatment. So make certain that you only take the recommended dose, and only use it on the surface, don’t ever swallow it. Peppermint oil is absorbed through the skin so even small amounts could be toxic. So although it sounds like it would be effective, you might want to hold off on using peppermint oil until studies establish that it’s safe.