herpes simplex
"I, too,  thought Abreva was magic.. for awhile. It was so reliable. If I caught the tingle early enough,  no cold sore developed.  If it was already in progress,  it healed so quickly and painlessly. It always worked and so I gladly paid the high price. 
A little over a year ago, I  got one that started on my nose and took over half of my face.  It got infected and I needed two types of antibiotics. I didn't suspect the Abreva,  until now.  This week, I used Abreva on a really small one on my lip,  and now it's all the space between my lip and nose,  advancing toward my eye,  and I'm so swollen I can't eat. Antibiotics again. Goodbye Abreva.  Forever."