However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Read more about some other popular AHA's here:

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

You'll most likely find this ingredient in cleansers where it is used to create a gel-like texture. As an emulsifier, it also prevents ingredients from separating.

There is much debate on whether this ingredient is comedogenic. The short answer - comedogenic ratings don't tell the whole story. Learn more about comegodenic ratings here.

The concensus about this ingredient causing acne seems to be divided. Research is needed to understand if this ingredient does cause acne.

Scrubs may use salt as the primary exfoliating ingredient.