There are three considerations to make when selecting the right glycolic peel for your skin:

(1) the concentration of acid in the overall solution,
(2) the pH of the acid, and
(3) whether the acid is buffered or unbuffered.

With respect to (1), it is prudent to first consider a low-concentration solution (20%-30%) and apply it for a short duration (1 to 2 minutes) to a small patch of skin, preferably where the skin is thick, like the upper arms. If redness or irritation does not persist after the peel has been removed, then it may be considered safe to apply the peel to the target location and adjust the length of time based on the location (less time for where the skin is thin, such as the facial region). Since glycolic acid is a keratolytic agent, some redness and irritation is to be expected while the peel is on the skin. However, should redness or irritation linger after the peel is removed, then the acid concentration is probably too strong.

With respect to (2), one needs to find a balance between efficacy and safety. Though glycolic acid's natural pH is 0.6, the OTC limit for home peels is 2.0 (as a point of reference, the pH of healthy skin is 5.5). Though it's technically possible for someone to burn themselves with a pH as high as 5, most people will do well working with a home peel between pH 2.0 and 2.8. To some extent, you can control the impact of a solution's pH by the length of time you leave it on your skin. In other words, the longer you leave a solution on, the deeper the absorption. A pH of 2.1 offers safety, flexibility, and efficacy for the majority of skin types and applications.

And with respect to (3), it is imperative that a home user select a buffered peel. Buffering serves the dual purpose of raising a solution's pH and changing its reactivity to water. If a solution is buffered, it can be completely removed with water alone. An unbuffered solution must be neutralized on the skin before it can be safely removed. A typical 70% glycolic peel is not buffered, has a natural pH of 0.6 and is sold to dermatologists for the treatment of severe scarring.