Comparing Salicylic Acid and Azelaic Acid in Acne Treatment

Acne is a complex and challenging skin disease with several treatments depending on its severity. It is known for pimples and blackheads, which in severe cases can turn into painful cysts and nodules that leave scars that can be extremely detrimental to self-esteem.

Experts prefer the combined regimen concerning treatment, where different active ingredients such as antibiotics, retinoids, benzoyl peroxide, and various acids, including salicylic and azelaic acid, are used. Not all at the same time, but a few at a time.

Acids, in particular, have different actions on acne. Each works at specific steps in the pimple pathway, and some serve more as adjuvants than as a treatment itself. Let's find out more about each one and how they work on acne below.

Steps towards the pimple

First, let's recap how a pimple develops to understand how azelaic and salicylic acid works.

As you may know, acne is a common skin disease known for the appearance of pimples, blackheads and, in severe cases, very painful nodules and cysts that can leave scars (1).

Briefly, the steps necessary for a pimple to occur are:

1. Overactive sebaceous glands, resulting in an overproduction of sebum (that annoying facial oil).
2. Cells become cohesive and do not normally shed onto the skin's surface (hyperkeratinization), leading to a keratin plug.
3. Trapped sebum leads to comedones (blackheads) and encourages the growth of skin bacteria such as Cutibacterium acnes (formerly Propionibacterium acnes).
4. As a result, inflammation occurs, shaping the red, painful and swollen pimple.

Genetics also plays a significant role, mainly since those with close relatives with acne are likely to also suffer from acne. Furthermore, sebum production is controlled by hormones and mediators (androgens in particular), which negatively influences blackheads' appearance (2).

Salicylic acid

Salicylic acid is a type of phenolic acid and beta hydroxy acid derived from the metabolism of salicin. In addition to being chemically similar to but not identical to the active component of aspirin (acetylsalicylic acid), it is best known for its use in acne treatments (3).

It comes from plants, characteristic of about 36 plants, and its derivatives are widely used in a broad range of diseases up to in products manufacturing (3). But let's get to the point, acne.

International recommendations, such as those published by the European Academy of Dermatology (4), the American Academy of Dermatology (5), and the Dermatological Society of Singapore (6), do not include salicylic acid as a first active ingredient in the treatment of acne.

What does that mean? That it does not confer a truly curative effect on its own, and its action focuses more on enhancing the effects of the principal treatment (6). With this in mind, topical salicylic acid can be used as an adjuvant to boost the primary treatment in two ways: as a cosmeceutical and a medical-grade peel.

A cosmeceutical is a topical preparation sold as a cosmetic but with performance features that suggest pharmaceutical action (7). However, they are not always necessary.

On the other hand, a chemical peel produces a controlled injury to the skin by applying a chemical agent that causes exfoliation of the skin's surface layers, leading to the removal of the old skin followed by the regeneration of new skin (8).

Salicylic acid works in many ways as an exfoliating agent. It is a comedolytic that stimulates skin desquamation, normalizes keratinization and somehow decreases inflammation, but not to a big extent (9).

Its concentration varies from 0.5% to 3.0% as an over-the-counter cosmeceutical, and you can find it in creams, lotions, washes, pads, among others products. Salicylic acid chemical peeling is done with professional products at higher concentrations, such as 20 to 30%, and seeks to normalize keratinization and promote the regeneration of new skin (9).

Recent studies

Although not a star ingredient in acne treatment, recent studies show that salicylic acid can provide similar results to leading medications such as benzoyl peroxide and adapalene (retinoid). An investigation proved that 2% salicylic acid hydrogel effectively reduces papules/pustules and other inflammatory acne lesions after a 28-day treatment regimen. In addition, it is safe to use and does not cause irritation (10).

Higher concentrations of up to 30% are even more effective in reducing blackheads, blemishes, and scars under controlled exfoliation in medical settings led by a health professional (8).

Azelaic acid

Azelaic acid is a naturally occurring saturated acid with profound anti-inflammatory, antioxidative and bactericidal effects (2). In contrast to salicylic acid, the treatment recommendations of the international organizations mentioned above include azelaic acid in their treatment guidelines.

Azelaic acid is one of the main active ingredients in treating comedonal acne, mild to moderate papulopustular acne up to severe with nodules and cysts (4,5,6). Since acne treatment should focus on the pimple course, azelaic acid effectively addresses the steps involved.

How azelaic acid works on acne?

Decreases inflammation

Azelaic acid decreases pimple swelling by suppressing chemical mediators involved in inflammation and scavenging reactive oxygen species (ROS) (2). A ROS is an unstable oxygen-containing molecule that readily reacts with others within the cell. An accumulation of ROS in cells can damage DNA, RNA and proteins, steps on the way to aging.

Fights bacteria

Most of the bacteria in acne skin are C. acnes, Staphylococcus epidermidis, and Malassezia furfur. Azelaic acid fights them by inducing changes in their internal structures.

Unlike antibiotics, no azelaic acid-resistant germs have been detected, so it is an ideal treatment approach since many bacteria get resistant and cause pimples to reappear over time and undoubtedly lead to treatment failure (2).

Prevents cell cohesion (hyperkeratinization)

Azelaic acid leads to modification of epidermal keratinization by reducing the size and number of keratohyalin granules and filaments (existing within the skin's stratum granulosum), returning them to normal (11).

Proven effectiveness

Numerous scientific studies confirm that it is effective in fighting acne. Although it is not suggested to be used alone, since the recommended approach for acne is the combined treatment, azelaic acid provides beneficial effects since it addresses the four key steps in pimple development (12).

For example, twice‐daily application of 20% azelaic acid cream can improve pimples within four weeks of starting therapy (13). Additional research showed that a 20% azelaic acid gel reduced the pimples by 60.6% and was 3.06 times more effective than a conventional moisturizer (14).

Another recent study shows that azelaic acid also works as a chemical exfoliant and improves acne in controlled medical settings at higher concentrations (15), and actually benefits acne when used with other main ingredients, such as antibiotics (16).

Conclusion

Both salicylic acid and azelaic acid work very well in treating acne; however, it should be noted that there is a big difference between their uses and recommendations.

It could be said, broadly speaking, that salicylic acid is not a must to treat acne, and it would be fine if it were not used daily, although it may provide benefits in addition to those provided by the primary treatment. Remember that whether or not to use a cosmeceutical depends on your physician's opinion.

On the other hand, Azelaic acid is part of the main treatment and plays a fundamental role in the battle against acne. It is considered in the topical treatment (applied directly to the skin) of many forms of acne, from the mildest to the most severe and is usually used with other main ingredients, either antibiotic, retinoids, or benzoyl peroxide.

When applying any of them to your face, you may feel itchy irritation and redness, but these side effects pass over time while the skin gets used to the ingredient. You can use cosmeceuticals to relieve the bothersome symptoms, such as moisturizers, gentle cleansers, and redness relief creams.

If you are struggling with acne, you must undergo a thorough dermatological examination to determine your degree and the treatment you require according to your condition. Consult your doctor and do not delay treatment. Pimples can worsen and leave scars that are more difficult to treat.