If you have a good understanding of exfoliation, then you might want to know some of the finer points of exfoliation.

The Effectiveness of an AHA Depends on its pH

AHA products must be formulated at the correct pH to be effective. For example, the pH must be acidic and lower than skin’s natural pH of 5.5. As you may recall from an earlier post on skin pH, skin is naturally acidic (slightly acidic).

If the AHA is at the same pH as skin, nothing happens.

The lower the pH, the more acidic the AHA. However, too acidic is harmful to skin.

In retail products, AHA exfoliants are always at a pH greater than 3.0.

A deep chemical peel that you get at a doctor’s office or medical spa is typically at a pH at or below 3.0. This is highly acidic and potentially destructive to skin if not administered correctly.

Only a trained and experienced skin care professional should administer a chemical peel below a pH of 3.0. In some states, estheticians are not allowed to administer exfoliants below a pH of 3.0. Only a physician or an esthetician under the supervision of a doctor can. (Esthetics laws vary widely from state to state.)

Unfortunately, AHA products almost never state their pH on the packaging. The only way to know the pH is to test it yourself. You can buy pH test strips at a drugstore.

Percent Concentration Also Matters for AHA’s

The effectiveness of an AHA also depends on its percent concentration (how much acid there is).

A higher concentration of acid is obviously more aggressive but more effective (up to a point).

AHA products with a high level of acid will state its concentration. For example: 15% Glycolic Acid.

Unless you know what you’re doing, or are under the care of a dermatologist or esthetician, you should not be using AHA’s with concentrations greater than 15-20%. Highly concentrated AHAs are harmful if your skin is not suitable for it or if you’re using it under the wrong conditions.

Note that Salicylic Acid (a BHA) will always have its concentration stated (in the U.S.). This is because Salicylic acid is an active ingredient that is considered a DRUG ingredient by the FDA. By law, all drugs must state their concentration on the packaging. Salicylic Acid typically appears in concentrations of 0.5 – 2.0%.

Enzymes are NOT pH-Dependent

You don’t need to worry about whether an enzyme exfoliant is formulated at the correct pH. Enzymes are not pH-dependent like AHA’s. An enzyme isn’t activated until it mixes with water.