Alpha hydroxy acid (AHA)
Glycolic Acid
The smallest-molecule AHA, generally considered the most potent of the common alpha hydroxy acids.
What it is
As the smallest common AHA molecule, glycolic acid is generally considered the most potent and fastest-acting of the mainstream alpha hydroxy acids. It's used across a huge range of formulations, from low-percentage daily toners and serums to higher-percentage professional or at-home peel treatments.
What it does
Glycolic acid is derived from sugar cane and is the smallest AHA molecule commonly used in skincare, which lets it penetrate the skin's surface efficiently and makes it a popular choice for texture- and dullness-focused exfoliation.
Who it’s for
People with normal, oily, or resilient skin who want a noticeable exfoliating effect; often not the first choice for very sensitive or reactive skin, where lactic acid is generally considered gentler.
Possible benefits
- Associated with smoother texture and reduced surface dullness
- Can support a more even-looking tone with consistent use
- Available in a wide range of formulation strengths for different experience levels
Irritation & compatibility considerations
Because of its small molecule size, glycolic acid is one of the more likely AHAs to cause stinging or irritation, especially at higher percentages or with too-frequent use. Sun sensitivity increases with use, making daily SPF essential. It's not usually layered with retinoids, other acids, or used on compromised skin.
How it fits into a routine
Night use, starting at low frequency (once or twice weekly) and building gradually. Often alternated with non-acid nights to give skin recovery time, and always followed the next morning by SPF.
Frequently Asked
Is glycolic acid too strong for beginners?
Not necessarily, but starting with a lower percentage and lower frequency is the general guidance for anyone new to acids, with lactic acid sometimes suggested as a gentler starting point instead.
Can glycolic acid be used every night?
Most general skincare guidance recommends a gradual buildup rather than nightly use from the start, and many people never move to nightly use at all — a few times a week is a common steady-state frequency.
Related Ingredients
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