Cold sore remedies can help slow or stop the viral infection in its tracks and help existing sores to heal more quickly. Using topical and internal remedies together will be most effective.
Cold sores are caused by the Herpes Simplex Virus-1 and have many triggers for an outbreak, including extreme temperatures, stress, illness or low immune function, diet and sleep changes. It can be worthwhile to track what your triggers are and then tailor a plan to reduce them and/or build up your immune system before encountering them.
The virus first infects the skin cells around the lips and then it spreads to the nearby sensory nerve cells where it “lives”. Though the immune response clears the virus from the skin area (resulting in the actual sore), the virus stays dormant in the neurons. They are reactivated by the triggers, which causes the cycle to start over once again. It is interesting to note that the immune system killing the virus is what actually causes the sore.
Herbs for Cold Sores
The following herbal approaches have a history of use and success as cold sore remedies.
Lemon Balm (Melissa officinalis) is useful both as a tincture and essential oil. It is an antiviral herb with the benefit of soothing nerve pain and nervousness.
I have seen the tincture work effectively to help sores to heal up quickly though some reports say the essential oil is more potent. Both lemon balm essential oil and tincture can be found at here, a supplier of very high quality herbs and herbal products.
When you first feel the “tingling” sensation, begin to apply the tincture or diluted essential oil. You can also take the tincture internally or drink lemon balm tea to hasten the healing process!
Black walnut (Juglans nigra), particularly the green hulls, is high in iodine which is 
helpful for healing the sores. Black walnut also is a strong antiviral herb, along with being astringent and contracting, making it a well rounded cold sore remedy. Make a decoction of the hulls and dab the liquid to the cold sores. Or make a medicinal oil with the hulls and apply that to the cold sore.
Here in the northeast U.S., the hulls fall off the tree in late September/early October. There is generally an abundance so you can stock up on some fresh medicinal oil! I would make the oil using the fresh hulls in olive oil. I have used black walnut hulls as a plant dye which creates a dark brown depending upon the concentration.
Other herbs that are useful in dealing with cold sores and herpes virus:
Myrrh (Commiphora myrrha) is an antiseptic, astringent and antiviral herb resin which can help to heal the sore as well as combat the virus. Both the tincture and essential oil (diluted) can be useful.
Spilanthes (Acmella oleracea) is often used for gum and teeth health because of its antiseptic and numbing properties. Here is a great article all about spilanthes written by Natalie Vickery of The Family Herbalist. Spilanthes extract can be found at Mountain Rose.
Yarrow (Achillea millefolium) is astringent and dry, so it will help to hasten the healing of the sores. It is another wild plant and is easily wildcrafted, flowering in mid to late summer.
Astragalus (Astragalus membranaceus) is an immune system tonic, making it very useful for overall health and for the prevention of cold sore breakouts.
Aloe vera is another specific remedy for cold sores. You can grow your own indoors or purchase the (minimally processed) gel.
Mushrooms, including reishi, maitake and shiitake are all wonderful for the immune system and for stimulation of white blood cells which can assist in ushering off the invading viral cells. Many mushroom extracts are on the market nowadays and the extract is a great way to use them as medicine.
Cloves (Syzygium aromaticum) contain a compound called eugenol which has direct action against the herpes virus. The essential oil is extremely strong and should only be used highly diluted.
St. John’s wort (Hypericum perforatum) is an herb specific for nerve pain. As the herpes virus stays dormant within the neurons near the lips, Hypericum can help to relieve pain associated with breakouts. Hypericum oil is blood red and a great way to use this herb for cold sores.
How to Use Herbs as Cold Sore Remedies
The following herbs can be used internally as cold sore remedies, as teas or tinctures:
- Lemon Balm
- St. John’s Wort
- Spilanthes
- Astragalus
Please do your research before using herbs internally.
Topically, I would make a strong herbal oil infusion using a selection of the herbs above and add to it the essential oils. Alternatively, stick with just one herb and test how your body reacts to it. I love this. It is the best way to know what works for you! Lemon balm would be a great one to start with and is readily available.