Overnight Glycolic Acid: Does Leave-On Exfoliation Actually Work?
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Glycolic acid is one of the most familiar names in skincare, but the difference between a quick salon peel and a leave-on product you apply at home can be confusing. Here is what the research says about glycolic acid used as a leave-on treatment, and how to approach it without overdoing it.
What glycolic acid is
Glycolic acid is an alpha-hydroxy acid, or AHA. It is a small, water-loving molecule that works on the surface of the skin by loosening the bonds between dead skin cells, which helps them shed more evenly. That is why it is associated with smoother texture and a brighter look over time.
What the research found
In a small pilot study published in the Journal of the American Academy of Dermatology, a leave-on lotion containing 25 percent alpha-hydroxy acid, including glycolic acid, was applied to the forearm for an average of six months. The researchers measured roughly a 25 percent increase in skin thickness, along with improvements in several markers of sun-aged skin, and no inflammation was seen (Ditre et al., 1996, PMID 8642081). This was an early study on a small number of people, so it is best read as supportive rather than the final word.
Later work on alpha-hydroxy acids in human skin has continued to describe measurable changes in the epidermis and the skin's response, which is part of the rationale behind using these acids in skincare (Yamamoto et al., 2006, PMID 16469079).
Why apply it overnight
Many at-home glycolic products are designed to be left on while you sleep. This gives the acid time to work without sitting under makeup or daytime sun exposure. AHAs can make skin more sensitive to the sun, so daily sunscreen the next morning is important.
Using it sensibly
- Start a couple of nights a week and build up only if your skin stays comfortable.
- Avoid layering it with strong retinoids or other acids on the same night when you are starting out.
- Follow with a moisturiser to keep the barrier comfortable.
- Wear sunscreen every morning.
At Verdo in Parnell we stock the Medik8 Sleep Glycolic, a leave-on overnight glycolic treatment, and the Medik8 Balance Moisturiser with Glycolic Acid Activator for a gentler daily option.
Disclaimer: This article is for general information only and is not medical advice. The studies cited are from peer-reviewed journals and are provided for educational context. Individual results vary. Speak with a qualified healthcare professional or dermatologist before changing your routine. Verdo Cosmetics makes no therapeutic claims about the products or services mentioned.
