Mandelic Acid Vs Salicylic Acid

Both of these acids are beneficial for the skin. Let’s break down exactly what each of these ingredients are, how they work, and which one may be better for you!


As you can glean from the heading, mandelic acid is an AHA.


AHA stands for, you guessed it, alpha hydroxy acids.

These are a type of active ingredient that have certain notable properties.

Active ingredients work to increase cell turnover (make dead skin cells shed faster).

Alpha hydroxy acids can be used as peeling agents to slough off dead skin cells on the surface of the skin.

Depending on the type of AHA used, the acid may penetrate more or less into the skin. This is largely dependent on the molecular weight of the acid – smaller acids penetrate more deeply while larger acids are characterized by less penetration into the skin.


AHAs differ from other acids in multiple ways.

The most glaring characteristics of AHAs include desquamation of skin cells, reduction of hyperpigmentation, smoothing skin roughness, and reducing the appearance of wrinkles. 

Desquamation Of Skin Cells

Desquamation involves proteolytic enzymes (1). These are enzymes that cleave or break apart proteins in the skin. Desquamation is the process by which skin cells are shed.

The skin follows a steady process.

Once epidermal cells become specialized, they form a strong structural barrier held together by corneodesmosomes. These are the rivets that hold skin cells together. 

After approximately 4 weeks, skin cells separate from this structure and desquamation occurs into the atmosphere (1).

This process of desquamation promotes a healthy skin state.

It prevents bacteria from entering the skin, and it is continuously shedding dead skin cells and making new cells to encourage the structural integrity of the skin barrier.

Reduction Of Hyperpigmentation

Hyperpigmentation is the darkening of certain areas of the skin due to sun damage, acne, or other types of skin damage from scarring.

Since AHAs are great at speeding up the process of skin shedding, it significantly reduces the look of dark marks that are on the surface of the skin.

Layer by layer, an AHA sheds dead skin cells and the pigmentation that comes with it.

Reduces The Appearance of Wrinkles

Due to factors like aging, genetics, and pollution, wrinkles are slowly formed on the skin.

A major reason for this is the noticeable decrease in sebum production as we age.

Sebum, otherwise known as “oil”, continuously moisturizes the skin and keeps it supple and smooth.

A lack of sebum production causes the skin to dry out and increases the possibility of wrinkling. 

A study showed that only after a few weeks of using mandelic acid, sebum production in both the right and left cheeks increased (2).

More oil means more moisture. This means reduced wrinkling and a better more moisturized skin barrier.

It has also been shown that using mandelic acid peels on the skin promotes an increase in collagen production in the skin (2).

A reduction in collagen is a marked effect of wrinkling. Increasing collagen supports a healthy skin barrier and less wrinkles.


Salicylic acid is a more commonly known acid available over the counter in concentrations up to 2%. 

It is an active ingredient mainly targeted to those suffering from acne and blackheads.

Salicylic acid is a type of beta hydroxy acid (BHA).

It dissolves easily in oil and breaks up cell junctions. These junctions are called desmosomes, which are the “rivets” that hold skin cells together (3).

By breaking up these rivets, salicylic acid exfoliates the skin. It encourages dead skin cells to shed and new skin cells to form.

It plays a role in improving acne, pigmentation, and photo damage in the skin (3). 


Improves Acne

A major effect of salicylic acid is improving acne. By interfering with the “glue” that holds skin cells together, it sloughs away the oil, dirt, and debris that contributes to comedones on the skin. 

The way that salicylic acid does this is by interfering with the desmosomal proteins in the skin, like desmoglein (3). It unclogs the pore and prevents new acne infections from forming.

It has been shown that salicylic acid in the form of both leave-on treatments and cleansers are effective at reducing acne lesions.

Reduces Post-Inflammatory Hyperpigmentation

Post-inflammatory hyperpigmentation is the darkening of skin after an inflammatory lesion has healed.

The dark colour of the skin is made by melanocytes, which are pigment-forming cells (4). These contain small structures called melanosomes that produce melanin, the substance that causes the dark colour.

Use of a BHA sloughs away skin cells, revealing new, healthier skin cells. 


A 12-week study conducted to determine the effects of both mandelic acid and salicylic acid together showed a 70% decrease in acne after the treatment (5).

In addition, comedones, papules and pustules were all reduced with this treatment. 

Improvement was also shown in the level of post-acne pigmentation in the patients.

This shows that multiple treatments can work together and have beneficial effects on the skin.


If your skin concerns are primarily geared towards preventing aging, mandelic acid is the way to go. Salicylic acid is targeted towards those suffering from acne and post-acne pigmentation.


  1. Del Rosso JQ, Levin J. The clinical relevance of maintaining the functional integrity of the stratum corneum in both healthy and disease-affected skin. J Clin Aesthet Dermatol. 2011 Sep;4(9):22-42. PMID: 21938268; PMCID: PMC3175800.
  2. Wójcik A, Kubiak M, Rotsztejn H. Influence of azelaic and mandelic acid peels on sebum secretion in ageing women. Postepy Dermatol Alergol. 2013 Jun;30(3):140-5. doi: 10.5114/pdia.2013.35614. Epub 2013 Jun 20. PMID: 24278065; PMCID: PMC3834725.
  3. Arif T. Salicylic acid as a peeling agent: a comprehensive review. Clin Cosmet Investig Dermatol. 2015 Aug 26;8:455-61. doi: 10.2147/CCID.S84765. PMID: 26347269; PMCID: PMC4554394.
  5. Sarkar R, Ghunawat S, Garg VK. Comparative Study of 35% Glycolic Acid, 20% Salicylic-10% Mandelic Acid, and Phytic Acid Combination Peels in the Treatment of Active Acne and Postacne Pigmentation. J Cutan Aesthet Surg. 2019 Jul-Sep;12(3):158-163. doi: 10.4103/JCAS.JCAS_135_18. PMID: 31619887; PMCID: PMC6785964.


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