As a normal side effect you can experience a very light peeling. There is no risk of exfoliation, no dryness, no redness and no sun sensitivity at all. You should know that...

...the whitening action can be sometime more visible on certain parts of the face compared to others, especially if you are having hormonal therapies / antibiotics. Waiting for the end of the medical treatment and applying the YW products uniformly let you prevent this side effect.

If the a skin is inflamated or with nodes it might become darker in some parts during the first applications, so do not apply the products on inflamated skin and scars. Do not use them on pregnant women and children to avoid the above mentioned changes. You may or may not experience any or some of these side effects. Some users are even delighted when they experience these side effects because it tells them the products are starting to work.