Short Answer:
Ice, tea bags, lemon balm and many more.
Long Answer:
Pressing or rubbing ice on a sore is possibly the best-known home remedy for cold sores. If the ice is applied early in the development of the cold sore, it can slow down the growth of the area around the cold sore. It is effective to hold the ice on the sore for a few minutes every ten minutes for a few hours. The ice will also help to make the sore smaller and keep the virus from moving or spreading.
Use a warm tea bag on a cold sore. Press it to your mouth for 20-30 mins.
Use Echinacea and goldenseal extract mixture. Echinacea is an immune system booster that can also prevent a cold sore outbreak. Take one dropper-full a day for no more than 3 days. Also put a few drops on a cotton ball and place on the affected area for a few minutes several times a day.
Lemon balm contains a high concentration of polyphenols and appears to minimize herpes outbreaks. It can be applied topically in cream form. Or brew as a tea lemon balm can be taken internally as it has antiviral qualities.
Olive leaf extract is good as a natural antibiotic for viral infections.
L-Lysine fights that virus that causes cold sores. Take 500 mg twice a day.
Vitamin B complex is very important for healing and immune system functions. Take 100 mg of each major B vitamin twice a day.
Place a small amount of salt on the cold sore and hold it in place with your finger for a minute or two. This may be painful but it is one of the quickest ways to heal cold sores.
Cut garlic in half and place one part on the cold sore. A compound in garlic cold Kyolic has antiviral properties which speeds healing. Take 2 garlic capsules a day.