Lactic Acid (AHA)
What it is
Lactic acid is an alpha-hydroxy acid (AHA) naturally present in sour milk and produced endogenously as a component of the skin's natural moisturising factor (NMF). As the second-smallest AHA molecule after glycolic acid, it penetrates effectively while causing comparatively less irritation due to its larger molecular size. Beyond keratolytic activity, lactic acid exhibits unique humectant properties and stimulates ceramide synthesis, distinguishing it from other AHAs and making it particularly suited for dry or sensitive skin types.
What it helps with
- Promoting controlled desquamation of the stratum corneum
- Stimulating ceramide production and improving barrier function
- Increasing epidermal and dermal hyaluronic acid content
- Reducing the appearance of fine lines and photoageing
- Fading superficial hyperpigmentation
- Improving overall skin radiance and texture
Common concerns it addresses
Best for
Clinical suitability
- Appropriate for patients with sensitive or reactive skin seeking exfoliation
- Indicated for those with concurrent dryness and textural concerns
- Suitable for keratosis pilaris management
- Beneficial as a gentler alternative to glycolic acid
- Generally avoided in pregnancy (as with most AHAs) — discuss with prescriber
Use with caution
- Sensitive or rosacea-prone skin — introduce very gradually
- Those using retinoids should avoid layering — alternate evenings if necessary
- Active eczema or dermatitis — defer until inflammation resolves
- Pregnancy — topical AHAs are generally advised against; seek guidance
Not ideal for
- Severely compromised skin barriers — stabilise first
- Immediately post-procedure before re-epithelialisation
- Those unable to commit to daily SPF use
- Patients seeking aggressive exfoliation — glycolic acid or peels may be more appropriate
How it's commonly used
Lactic acid is available at concentrations from 5-12% for home use. Begin with lower concentrations (5%) applied 1-2 times weekly, increasing frequency as tolerance develops. Apply to dry skin in the evening; rinse-off formulations may be preferable for sensitive individuals. Mandatory SPF use the following day due to increased photosensitivity. Avoid concurrent use with retinoids or other exfoliants to prevent over-exfoliation.
Pairs well with
Clinic note
Lactic acid represents our preferred introductory AHA for patients new to chemical exfoliation or those who have found glycolic acid excessively irritating. Its hydrating properties make it uniquely suited for patients presenting with both textural concerns and underlying dryness. For keratosis pilaris, we frequently recommend lactic acid body products as a well-tolerated, effective intervention. As with all exfoliants, we emphasise gradual introduction and consistent photoprotection.
Ingredient-focused product examples
Clinically curated examples featuring this ingredient. These are optional references to help guide your product research.
Gentle Resurfacing Serum
Mild exfoliating serum that smooths texture and enhances radiance without compromising skin hydration.
View productHydrating AHA Toner
Balanced formula combining gentle exfoliation with moisture-boosting properties for a brighter complexion.
View productThis content is provided for educational purposes and does not replace personalised medical advice. Individuals with skin conditions, those who are pregnant, or those undergoing dermatological treatments should seek professional guidance before introducing new active ingredients.
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