Fever blisters, also called cold sores (caused by the herpes simplex virus-1, HSV-1) occur usually on the lower lip, but can also occur on the upper lip (even throat, nose, chin, inside cheeks, gums and roof of the mouth). These always occur in the same place on the lip. These often appear during stress, sick times with cold – flu – other, pregnancy, but also with prolonged exposure to sun or cold. Cold sores are contagious and direct contact with other people should be avoided (also toothbrush, utensils, towel) to prevent transmitting the virus that causes the sore until it is healed. Keeping the sore area covered with a cream or ointment until healing is completed will make things more comfortable – be sure to wash hands before/after application (better with glove or Q-Tip).
For regular cold sore sufferers there is an excellent prescription cream that works very well: Denavir (applied every 2 hours at the immediate onset of symptoms can prevent blistering from even occurring). Unfortunately, there is no generic yet available and without prescription drug coverage it has become extremely expensive.
Another significant option for regular cold sore sufferers is to preventively take Valtrex tablets (Rx required) before those situations that usually bring on cold sores (prolonged exposure to cold / sun).
Lysine, an essential amino acid (of the twenty-two standard amino acids, eight are called essential amino acids because the human body cannot synthesize them), has long been reported to be a helpful nutritional adjunct in preventing cold sores. A adult daily dose of 500 mg appears to provide quite a preventive benefit.
Abreva is an over-the-counter cream for the treatment of cold sores; however, note that it prevented from proceeding to blister stage only 34% of the time, and reduced healing time by only one day (clinical results).