Ever since I started experimenting with and consulting people on supplements, in my experience one of the most consistently effective has been the amino acid L-Lysine for cold sores. Yet like many natural products used against infections you have to take enough of it, and the sooner you start it after an outbreak begins, the better.
L-Lysine is another example where I can only rely on my personal experience to relay truthful information to you, because of Health Canada restrictions. This is despite the fact that L-Lysine has been used as a natural health strategy to combat cold sores for decades, and articles on the topic abound on the internet.I was first introduced to and used L-Lysine for cold sores in the early 1980's!
(Such Health Canada censorship is about to get much worse after the next federal election! More info on this to come soon!)
In my experience I have also seen L-Lysine be effective for herpes zoster virus that causes shingles, despite trials that refute this. Be clear that the recommendations below apply to adults, not children.
How to take L-Lysine for best results
Firstly - for it to be most effective you have to take L-Lysine on an empty stomach. This is because it will compete for absorption with other amino acids of similar structure, such as L-Arginine and L-Ornithine.
Secondly - you have to take enough. Though dosage recommendations vary from as low as 1000 mg twice per day to up to 3000 mg 3 times per day, I have always found that taking 2000 to 2500 mg (4-5 capsules) four times on the first day of treatment, three times on days 2 and 3, twice on day 4, and then as needed to finish getting rid of the cold sore often works very well.
Though I have never seen a bad reaction to L-Lysine, if you are concerned about taking too much then limit yourself to a total of 9 grams (9000 mg) per day. 
Why is it so effective?
As for why it is effective, cold sores are caused by the herpes simplex virus, which selectively concentrates and uses another amino acid: L-Arginine. L-Lysine is antagonistic to L-Arginine helping offset its uptake and concentration in the cells, thereby suppressing growth conditions needed by the virus.(1, 2)
Which products work the best?
Some formulations try to take advantage of other synergistic ingredients like echinacea, or zinc, such as the Quantum™ Super Lysine+.  Personally, the formulas I have seen be most synergistic with L-Lysine are Amazon AV by Raintree, for both cold sores and shingles...or formulas containing bee propolis such as our Bee Immune formula, with propolis, echinacea, zinc, garlic and a host of other antimicrobials.
L-Lysine is an essential amino acid that plays many important roles in the body, such as being necessary to form connective tissue, including within our bones. Those who use heart or circulatory supplements may be familiar with seeing it in formulas designed to keep your blood vessels strong, yet flexible, such as CardioFlex™.
Notably, L-Lysine is also a necessary precursor for the bodies production of L-Carnitine, which is important for heart health and being able to burn fat efficiently.
The herpes family of viruses: nuisance or serious concern?
Being somewhat prone to both cold sore and shingles, L-Lysine is something that I have incorporated into my supplement regimen for many years now, as I believe the inflammation caused in our nervous system by the herpes virus can contribute to many neurological conditions, including Alzheimer's and dementia.
Personally, when I find my brain not performing the way I want it to, I will often take some extra L-Lysine, and some Amazon AV, and find it helps about 80+ % of the time.
Bottom line...don't underestimate this virus in causing neurological and cognitive deficits, particularly in older age!
Until next time,
mechanism of L-Lysine actions against HSV-1