Glycolic Acid + Vitamin C (L-Ascorbic Acid)
Use With Caution
These ingredients can be combined, but require careful timing, lower concentrations, or gradual introduction.
Vitamin C and glycolic acid can work together, but the low pH of both may cause irritation in sensitive skin.
What the Research Says
L-ascorbic acid (the most potent form of vitamin C) and glycolic acid are both acidic ingredients that work best at low pH. L-ascorbic acid is most stable and effective below pH 3.5, and glycolic acid products typically range from pH 3.0-4.0. Layering two low-pH products can create cumulative irritation, particularly on sensitive or newly-exfoliated skin. This is the primary concern - not a chemical incompatibility.
That said, the combination is actually synergistic for anti-aging and brightening. Vitamin C is a potent antioxidant that inhibits melanin production and stimulates collagen synthesis. Glycolic acid accelerates the turnover of pigmented cells and enhances vitamin C penetration. Together, they address hyperpigmentation, fine lines, and dull skin more effectively than either alone.
The practical approach depends on your skin's tolerance. If you have resilient skin that tolerates acids well, using both in the same morning routine (glycolic acid, wait, then vitamin C) is fine. If you have sensitive or reactive skin, separating them into different times of day is the safer choice. Vitamin C derivatives like sodium ascorbyl phosphate or magnesium ascorbyl phosphate are more pH-neutral and can be layered with glycolic acid more easily.
Timing & How to Use
For tolerant skin: apply glycolic acid first, wait 15-20 minutes for pH to normalize, then apply vitamin C serum. For sensitive skin: use vitamin C in the morning and glycolic acid in the evening. Start with lower concentrations of both.
Practical Tips
- 1Vitamin C derivatives (ascorbyl glucoside, sodium ascorbyl phosphate) are gentler to layer with glycolic acid than pure L-ascorbic acid
- 2If you experience stinging when layering, separate them into AM and PM routines
- 3Store vitamin C products properly - oxidized (brown/orange) vitamin C is less effective
- 4The combination is particularly powerful for brightening and hyperpigmentation
- 5Always use sunscreen - both ingredients increase photosensitivity
References
- Telang PS. Vitamin C in dermatology. Indian Dermatol Online J. 2013;4(2):143-6.
- Farris PK. Topical vitamin C: A useful agent for treating photoaging and other dermatologic conditions. Dermatol Surg. 2005;31(7 Pt 2):814-7.
- Al-Niaimi F, Chiang NYZ. Topical vitamin C and the skin: Mechanisms of action and clinical applications. J Clin Aesthet Dermatol. 2017;10(7):14-17.
