Glycolic acid: what it is for, benefits and how to use it

The mechanism of action of glycolic acid is well documented in the dermatological literature. It acts on four levels at once:

• It dissolves the corneodesmosomes, the protein bonds that hold the dead cells of the stratum corneum together.
• It speeds up cell renewal, helping young keratinocytes reach the surface sooner.
• It stimulates the fibroblasts, which translates into gradual collagen production and improved firmness.
• It improves the penetration of other active ingredients applied afterward (moisturizers, antioxidants, depigmenting agents).

“This process translates into more even, radiant skin with better texture. But the result depends on the concentration, the pH and the frequency of use.” Cristina Cobaleda

Benefits of glycolic acid

The visible effects after continued use under a proper protocol include:

• Smoother texture: it reduces roughness and evens out the skin's surface.
• More even tone: especially effective on superficial dark spots and post-inflammatory acne marks.
• More radiance: by removing dead cells, the skin reflects light better.
• Support for acne-prone skin: it keeps pores clear and reduces the formation of comedones.
• Gradual anti-aging effect: with consistent use, it promotes collagen synthesis and improves fine lines.

To address deeper or long-standing dark spots, glycolic acid is usually combined with other clinical treatments such as IPL photorejuvenation or specific facial rejuvenation treatments.

Recommended for:

• Dull skin or skin lacking radiance.
• Uneven texture and visible pores.
• Superficial dark spots and post-inflammatory marks.
• First signs of aging (fine lines, expression lines).
• Combination or oily skin prone to comedones.

Use with caution or avoid in:

• Sensitive or reactive skin that has not been gradually accustomed to it.
• Rosacea or active couperose.
• Atopic or seborrheic dermatitis during a flare-up.
• Wounds, open lesions or freshly waxed or shaved skin.
• Pregnancy (especially at high concentrations; always consult first).

“In these cases it is essential to consult a professional before starting any routine with acids.” Cristina Cobaleda

How to add it to your routine: step-by-step protocol

• Gentle cleansing with a cleanser free of harsh sulfates.
• Balancing toner (optional, alcohol-free).
• Glycolic acid on dry skin, avoiding the eye contour and mucous membranes.
• Wait 5–10 minutes before the next product.
• Repairing moisturizer with ceramides or hyaluronic acid.
• At night only.
• In the morning, SPF 50 sunscreen without exception.

Recommended frequency:

• Beginner: 1–2 times a week.
• Intermediate: 2–3 times a week.
• Accustomed skin: up to 4 times a week.

A common mistake is using it every day from the start: the skin needs an adjustment period of 2 to 4 weeks.

What to combine with glycolic acid and what to avoid

Avoid combining

• Niacinamide (separate morning/night)
• Retinol and retinoids (at the same time of day)
• Hyaluronic acid
• Pure vitamin C at high concentration
• Ceramides and peptides
• Other AHAs/BHAs at the same time
• SPF 50 sunscreen (morning)
• Physical exfoliants (brushes, scrubs)
• Repairing moisturizers
• Toners containing alcohol

Combining it with retinol is not impossible, but it requires alternating (every other day) or using them at separate times. In the clinic, this type of combined protocol is designed as part of an individualized facial biorevitalization or anti-wrinkle treatment plan.

Glycolic acid and dark spots on the skin

One of the most requested indications in consultations. Glycolic acid helps fade superficial dark spots by speeding up cell turnover: pigmented cells are replaced sooner by new cells with more evenly distributed melanin.

However, it does not work the same way on every type of dark spot. To understand the origin of each type (solar lentigines, melasma, post-inflammatory hyperpigmentation) and which treatment is really effective in each case, we recommend reading the full guide: why do we get dark spots on our skin?.

For deep or long-standing dark spots, glycolic acid works best combined with complementary technologies such as IPL photorejuvenation or staged peel protocols.

Cosmetic glycolic acid has a ceiling on its effectiveness. It is worth consulting a specialist when:

• Dark spots do not improve after 8–12 weeks of consistent use.
• Persistent irritation, intense peeling or ongoing sensitivity appears.
• The goal is to treat acne scars, melasma or established wrinkles.
• You are considering starting a protocol with concentrations above 20%.
• You want to combine it with other potent active ingredients (retinoids, vitamin C, depigmenting agents).

At Instituto de Benito we work with medical-grade glycolic acid peels as part of personalized plans based on skin type, aesthetic goal and phototype. You can see real cases treated at the clinic to understand the realistic results this type of protocol offers.