Salicylic acid: a BHA active ingredient for blemish-prone skin

Salicylic acid is a beta-hydroxy acid (BHA) widely used in dermatological cosmetics for its gentle exfoliating effect on the stratum corneum and its benefits for blemish-prone skin, oily skin, and skin with visible pores. This FAQ details its properties, uses, synergistic effects, and the strict precautions that must be followed to ensure safe use.

What is salicylic acid, and how does it work on the skin?

Salicylic acid is a plant-derived compound historically obtained from the bark of the willow (Salix alba) and wintergreen (Gaultheria procumbens). Today, it is most often produced synthetically to ensure purity and stability. Its classification within the beta-hydroxy acid family gives it a lipid affinity, allowing it to penetrate the stratum corneum and act within sebum-rich pores, whereas alpha-hydroxy acids (AHAs) remain on the surface.

In cosmetics, salicylic acid acts as a gentle exfoliant that helps remove dead skin cells from the stratum corneum, unclog blocked pores, and improve skin texture. European regulations (EC 1223/2009) cap its concentration in cosmetics at 2% (rinse-off or leave-on, depending on the product’s intended use). Above this threshold, salicylic acid is classified as a drug and requires a specific pharmaceutical regulatory framework.

What are the benefits of salicylic acid for the skin?

The main recognized cosmetic benefits of salicylic acid are:

• Gentle exfoliating effect: it promotes surface renewal and smooths the skin’s texture.
• Support for blemish-prone skin: It helps manage acne-prone skin by unclogging pores and reducing shine.
• Comfort for blemished skin: It helps create a more even-looking complexion when used as part of a comprehensive skincare routine.
• Reduces the appearance of post-acne marks: It helps visually even out areas marked by past breakouts.
• Action on fine lines caused by dehydration: by promoting superficial exfoliation, it improves the skin’s smooth appearance.

In casesof inflammatory, cystic, or widespread acne, using a salicylic acid-based product alone is not enough: a dermatological consultation is essential to tailor treatment.

What skin types is salicylic acid suitable for?

Salicylic acid is particularly suitable for oily, combination, and blemish-prone skin , as well as skin with enlarged pores and blackheads. On combination skin, it can be applied topically to the T-zone (forehead, nose, and chin).

For dry, sensitive, atopic, or rosacea-prone skin, use with caution: opt for a low concentration (0.5 to 1%), a reduced frequency (1 to 2 times per week), and a formulation suitable for sensitive skin (a rinse-off cleanser rather than a leave-on serum). If you havea history of allergy to salicylates (such as aspirin), cosmetic salicylic acid should be avoided or used only under medical supervision.

How can you incorporate salicylic acid into your skincare routine?

Salicylic acid comes in several formulations: cleansers, lotions, serums, creams, and targeted treatments.

• Low-concentration cleanser (0.5% to 2%): Use once or twice daily to prepare the skin.
• Lotion or serum (1–2%): Apply 1–3 times a week, depending on tolerance, in the evening, on clean skin.
• Targeted spot treatment: Apply to the affected area, following the manufacturer’s instructions.

Salicylic acid causes skin photosensitivity: applying a broad-spectrum sunscreen with SPF 30 to 50 is essential every morning, even on cloudy days and indoors near windows. Failure to do so increases the risk of post-inflammatory hyperpigmentation and sun damage.

What are the side effects of salicylic acid?

Inappropriate or excessive use can lead to several adverse effects:

• Dry skin: disruption of the hydrolipidic film, which can weaken the skin barrier.
• Irritation, redness, and a tingling sensation: particularly on sensitive skin or when the concentration is too high.
• Excessive flaking: a sign of overly aggressive exfoliation.
• Temporary worsening of blemishes (purging) at the start of use in some people.
• Allergic reactions are rare but possible, especially in people with a known allergy to salicylates (aspirin).

To minimize these effects, start with a low concentration (0.5 to 1%), space out applications (1 to 2 times per week), moisturize the skin thoroughly, and do not combine with other exfoliating ingredients. A systemic reaction (facial swelling, difficulty breathing, generalized hives) requires immediately calling 15 or 112.

Can salicylic acid be combined with other active ingredients?

Salicylic acid combines well with certain active ingredients but should be used at separate times from others to avoid cumulative skin irritation.

Beneficial combinations:

• Niacinamide: supports the skin’s barrier function, reduces redness, and improves skin texture.
• Hyaluronic acid: counteracts the drying effect by restoring hydration.
• Zinc (PCA or gluconate): enhances the soothing effect on blemish-prone skin.
• Centella asiatica, bisabolol, allantoin: soothing active ingredients that balance BHA routines.

Combinations to avoid or space out over time:

• Cosmetic retinol: risk of cumulative irritation. Alternate days (BHA one night, retinol another night).
• AHAs (glycolic, lactic, mandelic acids): risk of excessive sensitization. Do not apply on the same evening.
• Vitamin C (pure ascorbic acid): Different pH conditions may affect efficacy; use at different times (morning/evening).
• Benzoyl peroxide: risk of mutual inactivation and significant irritation.