Cold sores (herpes simplex) are caused by a common virus of the chickenpox family that in another form may cause either genital herpes or shingles (herpes zoster).
Improve your general resistance by taking plenty of Vitamin C-rich fruits and vegetables. Avoid foods (such as peanuts and chocolate) that are rich in the amino acid argenine, which may have the effect of triggering an attack of cold sores. A supplement of the amino acid L-lysine is said to restrict attacks.
Drink herb teas made from Burdock, Yellow Dock, and Dandelion root. Boost the immune system by combining these with herbs such as Echinacea, and Licorice.
Locally, apply directly to the cold sore a diluted tincture of Calendula or Goldenseal.