A few small studies have indicated that using vitamin C both orally (in tablet form) and as a topical cream (applied directly to the cold sore) may speed up the rate of healing of cold sores.¹ The liquid form of vitamin C can be soaked in a cotton pad and applied to the cold sore several times a day, and it can be used along with vitamin C tablets (at least 600 mg). However, more research is needed before the long-term benefits of using vitamin C to treat cold sores can be confirmed. People with a history of kidney stones should avoid high doses of vitamin C.

Cold sores usually heal on their own without prescription medications or complementary therapies.