Here are some antiviral drugs.
(The ones with * you should take often as a supplement)
-Zinc*
-Vitamin C*
-Vitamin B6 (Pyridoxine)*
-L-Lysine
-NAC
-Raw Garlic or Garlic Powder (specifically allicin)
-Raw Red Onion
For Cold Sores, limit food with Arginine when you first feel a cold sore coming on until it goes away.
Make sure to periodically check the expiration date on the medicine