Chemical Peel Causes Fever Blisters

Hello,
The short answer is that peels of the face cause irritation of the skin. This irritation can "awaken" old viral infections, causing an outbreak with cold sores. Some people have the tendency toward these outbreaks.

If you have a history of "fever blisters", or oral herpes infection, any stress, irritation, bad sunburn etc, can initiate a recurrence or a new breakout. Many practitioners will will give patients an anti-viral medication to start prior to aggressive peels or laser treatments to minimize the risk of a breakout while you are healing from the peel.
The concern is that if you have a peel or some type of resurfacing of the skin that leaves "an open wound" and you develop a herpes recurrence , that could lead to delayed healing, unwanted pigment change or a scar. The chance of the happening can be almost eliminated if you start on Valtrex or Zovirax prior to your procedure and stay on the medicine, as directed by your doctor, until the skin is healed.