L-Lysine is an amino acid that is found in many foods including meat and eggs.  It is believed that this substance can inhibit the cold sore virus and may help reduce outbreaks and reduce outbreak duration.  You might already have this inexpensive supplement in your medicine cabinet.  If not, a quick trip to the drug store is all it takes.


It is recommended to take 2000-6000 mg of l-lysine per day during outbreaks and 2000 mg per day for suppression. Try to buy a brand made without gelatin-based capsules as these can contain l-arginine which negates the beneficial effects of L-lysine.

Internal vs. Topical

The effectiveness of this blood blister treatment is largely based on how you take the supplement. Many companies market topical products like lip balm, ointments and salves that contain l-lysine.  However, studies show that these treatments are largely ineffective.  To be effective, L-lysine needs to be taken internally at the recommended dosage above.

Lysine vs. Arginine

Arginine is an amino acid that acts as the antithesis of l-lysine.  Too much Arginine in the diet can lead to more outbreaks.  Arginine is found in nuts, meat, grains and gelatin products. If you know you will be eating any of these foods and are prone to blood blister outbreaks, make sure to supplement with l-lysine first to help negate the promoting effects.

L-Lysine Dosage: L-Lysine the amino acid is believed to be good at keeping blood blisters and fever blisters at bay. However, many people believe that only 500 mg a day is enough. In my experience, and based on studies I have read, people need to take between 3000 and 4000 mg a day in order to see benefits. I usually take 4 500 mg pills in the morning and 4 at night before bed. A month or so ago I wanted to see if I could get by on less, since I would rather take the least amount that is effective. So I started taking only 1500 in the morning and evening, and within a few days I had a new blood blister. I am not sure if this can be fully attributed to the lower dosage of L-Lysine but I can tell you now that I am back to taking 4 grams a day as I had been. Also, I found that the brand Finest Natural from Walgreens works the best. I had also switched brands to a CVS store brand the last time I had an outbreak, so I am not sure if that could also be the culprit. Of course, I am not a doctor so I am not claiming to know what I am talking about. It just worked for me. Please see your doctor before starting any medications or amino acids.