An esthetician recently told me that glycolic acid can lead to hypopigmentation. Is this true? I am currently trying to get rid of a hypopigmented scar. So my question is, can mild leave on glycolic acid or stronger glycolic peels cause skin to hypopigment?

Speaking just based on personal experience (using up to 70% glycolic to remove moles), the color of my skin where once the moles were has not changed a single bit. That is the skin is normal pink, just like everywhere else.

In one case I gradually removed a mole and the skin in that spot was slightly more pink, for about a month, but now you could not see a difference not even with a microscope.

So I doubt the statement of your esthetician is true. Also because if it was, then nobody would use glycolic acid!

the one thing of course you have to be careful is not to make scars by treating too aggressively. And like with any acid, you must not expose to sunlight (without protection especially) to avoid more damage from freshly peeled skin. But that's obvious with any peel.

I am afraid your esthetician only gave you some of the information and I would like to clear this up. It is not true that all gylcolic can create hypopigmentation in everyone. There's more to it than that.

High concentrations of an acid at a low pH (medium peel) can result in hypopigmentation in dark skin individual (Fitz Level III and above). For instance: 40% Glycolic acid at 1.9 pH should not be used on Fitz III or higher. Whereas a 40% Glycolic acid at 4 pH "might" be tolerated by a Fitz III but I would not recommend for a Fitz IV or V. The hypopigmentation results if the skin peeled too deeply or in darker skin.

Lower pecentage acids can be used by anyone without risk of hypopigmentation. Example: Skin Bio acids (LacSal, Exfol, our 15% Fruit Acid, 10% Lactic, 5% Salicylic)

Light skin individuals have a higher tolerance to acids and can typically tolerate stronger acids than those with color in their skin.

DianaYvonne