Best For Skin Types
All
Effective Concentrations
2–5%
What Is Maleic Acid?
Maleic acid is a dicarboxylic acid—a small organic compound with two carboxylic acid groups. In skincare formulations, it functions primarily as a pH adjuster and buffering agent, helping to maintain the stability and optimal pH of a product. It appears in only a small proportion of skincare products, typically at low concentrations.
As a buffering agent, maleic acid works behind the scenes to support formula stability rather than delivering direct benefits to the skin itself. It is used in cosmetics at concentrations that have been assessed as safe for topical application.
How It Works
Maleic acid works as a buffer by donating or accepting hydrogen ions, depending on the pH of the formulation. This helps resist changes in pH that might otherwise occur as a product ages or is exposed to light and air. By maintaining a stable pH environment, it supports the performance of other actives in the formula that may be pH-dependent.
Clinical Evidence & References
Published research on maleic acid in topical skincare is limited. Most safety data comes from toxicology studies at concentrations much higher than those used cosmetically. At the low levels employed in skincare (typically 2–5%), maleic acid has not been associated with adverse effects in standard safety assessments.
Its primary role is technical rather than therapeutic, so clinical studies measuring skin benefits specifically from maleic acid are sparse. Any observed skin improvements in formulations containing it would likely be attributable to other active ingredients rather than the maleic acid itself.
Published Research
How to Use
Maleic acid is not an active ingredient you need to dose or monitor yourself—it is incorporated by formulators at appropriate concentrations. Simply use products containing it as directed. Its presence helps ensure that other actives in the formula remain stable and effective over time.
Safety & Precautions
Frequently Asked Questions
From the Clinic
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