What Is Salicylic Acid and How Does it Help Heal Acne?
The Essential Information
Salicylic acid is the most common ingredient you will find in over-the-counter "acne-fighting" washes, pads, toners, spot treatments, and makeup, from 0.5% up to 2% strength, and is at least somewhat effective in treating mild-to-moderate acne. However, on its own it is unlikely to provide dramatic relief, so it is often used alongside other acne treatments for synergistic effects.
It can also be used in a professionally-administered chemical peel, where its effect is similar to other acids. However, again, chemical peels alone are unlikely to completely clear acne, and are also best used alongside other treatments to achieve satisfactory results.
Salicylic acid is easily absorbed into the skin, where it can help unclog pores and reduce inflammation. But at the same time, its ability to absorb into the skin can result in unpleasant or even dangerous side effects if high percentage salicylic acid products are used for too long or on too large an area of skin. Over-the-counter salicylic-acid-containing products should be safe, however, since they are limited to 2%.
- How Does Salicylic Acid Help Treat Acne?
- What Does the Research Say About Salicylic Acid in Acne Treatment?
- Side Effects and Toxicity
Salicylic acid is a compound derived from the bark of the willow tree, though the version used in modern medicine is synthesized in laboratories. It has medicinal qualities, including the treatment of acne and pain relief. In fact, a chemical variation of salicylic acid, called acetylsalicylic acid, is the active ingredient in aspirin.1
People use topical salicylic acid to treat acne, as well as to treat other skin conditions such as psoriasis. Topical salicylic acid comes in various concentrations. In the United States, over-the-counter products can contain from 0.5% to 2% salicylic acid; anything stronger needs to be administered in a esthetician/cosmetician or doctor's office or requires a prescription.2
How Does Salicylic Acid Help Treat Acne?
Topical salicylic acid is easily absorbed by the skin and exhibits three different properties that can help treat acne:
- Preventing clogged pores: It dissolves a protein that is present in the skin called keratin, which helps loosen skin cells so that they can be shed more easily, which keeps the skin turning over, thus helping to prevent clogged pores.2,3
- Clearing already-clogged pores: It clears clogged pores by penetrating into the pore and dissolving skin oil and dead skin cells, which helps loosen debris that is clogging a pore.4
- Reducing inflammation: It has anti-inflammatory properties that can help reduce the redness and soreness that is characteristic of acne.4
What Does the Research Say About Salicylic Acid in Acne Treatment?
The research that exists generally supports the conclusion that salicylic acid can be a useful component of acne treatment. While results are not dramatic, studies show that salicylic acid works consistently better than placebo, which means salicylic acid is the real deal, and does in fact help reduce acne to some degree.
Expand to read details of studies
A 1992 literature review in the journal Clinical Therapeutics looked four studies and one assay that assessed the effectiveness of 0.5-2% salicylic acid solutions in treating acne. In the studies reviewed, salicylic acid reduced the number and severity of acne lesions. The authors stated, "A review of four clinical studies and a comedolytic assay attests to the efficacy and safety of 0.5% and 2% solutions of salicylic acid for the treatment of acne vulgaris. In three placebo-controlled studies and a comedolytic assay, salicylic acid pads reduced the number of primary lesions and thereby the number and severity of all lesions associated with acne."5
A more recent 1996 study in the Journal of Dermatological Treatment investigated the effectiveness of a 2% salicylic acid lotion in treating mild to moderate acne. The researchers divided 114 university students into two groups: one group received salicylic acid lotion; the other group received a placebo (inactive substance). This study found that the group receiving salicylic acid experienced a greater reduction in acne lesions than the placebo group, especially after 8 and 12 weeks of treatment. Interestingly, salicylic acid reduced papules but not pustules in this study.6This is counterintuitive, because papules usually become pustules. The authors did not give a proposed reason for this outcome; one possible explanation is that the salicylic acid prevented papules from becoming pustules, but further research is necessary to explain this outcome.
A 2011 study in the Journal of the European Academy of Dermatology and Venereology compared the effectiveness of a combination tretinoin/clindamycin lotion and a combination salicylic acid/clindamycin lotion. This study found that both treatments resulted in a significant reduction in both inflammatory and non-inflammatory lesions. The group of patients receiving the tretinoin/clindamycin combination showed improvement sooner than the salicylic acid/clindamycin group, but by the 12-week mark, there was no significant difference between the two groups.3Researchers generally consider topical retinoids such as tretinoin to be more potent than salicylic acid, though salicylic acid typically has fewer side effects than tretinoin and is sometimes prescribed instead of tretinoin for this reason. This study, however, suggests that while tretinoin in combination with clindamycin may produce faster results, salicylic acid in combination with clindamycin eventually has a comparable outcome.
A 2012 study in The Journal of Dermatology explored whether adding salicylic acid to a clindamycin/benzoyl peroxide combination solution increased the effectiveness of the solution. In this study, researchers divided 50 patients with mild to moderate acne into two groups: one group received only clindamycin/benzoyl peroxide plus a placebo; the other group received clindamycin/benzoyl peroxide plus salicylic acid. This study found that the group receiving salicylic acid plus clindamycin/benzoyl peroxide experienced significantly more improvement in both non-inflammatory and inflammatory acne lesions than the group receiving only clindamycin/benzoyl peroxide. The authors speculated that the improvement experienced by the group receiving salicylic acid plus clindamycin/benzoyl peroxide might be due to the fact that salicylic acid helps clear pores of dead skin and sebum, thus allowing better penetration of the other medications.7
A 2013 study in the journal Skin Research and Technology tested the effectiveness of a 1.5% salicylic acid cream containing natural skin penetration enhancers (natural ingredients that help other ingredients penetrate into the skin). This study had two parts: (1) testing the effectiveness of the penetration enhancer in the lab; and (2) testing the combination salicylic acid plus penetration enhancer cream in patients. In the first part of the experiment, the researchers found that penetration into the skin of the combination product was twice that of salicylic acid without the penetration-enhancing cream. In the second part of the experiment, 20 patients with facial acne received this combination cream twice daily for four weeks. Results showed that 95% of patients experienced at least some improvement in their acne, and 20% experienced complete clearing of their acne. The researchers also found that both inflammatory and non-inflammatory lesions decreased during the four weeks of treatment.8This study needs to be interpreted with caution, however, for several reasons: some of the ingredients in the penetration enhancer product are already known to help reduce acne, so improvement might have been due to these ingredients rather than to the salicylic acid; the penetration enhancer was tested on pig skin, and thus we cannot assume that human skin would react the same way; and the authors of the study omitted crucial information that is always included in reputable research, such as a statement of any financial conflicts of interest that the authors might have.
Side Effects and Toxicity
Researchers consider topical salicylic acid to be a relatively safe and well-tolerated product at over-the-counter strengths. Side effects are usually infrequent, mild, and temporary. When side effects occur, they usually occur early in treatment and then subside within a few weeks. These side effects include:
- Discomfort at the application site
- Skin peeling
However, higher-percentage salicylic acid causes more severe side effects. According to a 2003 article in the American Journal of Clinical Dermatology, "At concentrations of 2% or greater, salicylic acid is likely to cause some degree of local skin peeling and discomfort."2
Caution: When used for a prolonged period of time or over large areas of skin, salicylic acid can be absorbed into the body and produce systemic (throughout the body) side effects. Possible systemic side effects include:
- Temporary damage to the inner ear
- Salicylate toxicity, which can be serious, with symptoms such as increased breathing rate, ringing in the ears or loss of hearing, generalized weakness, nausea, vomiting, diarrhea, and metabolic abnormalities such as elevated liver function tests2,9,10
- Vlot AC, Dempsey MA, and Klessig DF. "Salicylic acid, a multifaceted hormone to combat disease." Annual Review of Phytopathology. 47, 177-206 (2009).
- Akhavan A and Bershad S. "Topical acne drugs. Review of Clinical Properties, Systemic Exposure, and Safety." American Journal of Clinical Dermatology. 4(7), 473-492 (2003).
- Babayeva L, et al. "Comparison of tretinoin 0.05% cream and 3% alcohol based salicylic acid preparation in the treatment of acne vulgaris." Journal of the European Academy of Dermatology and Venereology. 25(3), 328-333 (2011).
- Higgs GA, et al. "Pharmacokinetics of aspirin and salicylate in relation to inhibition of arachidonate cyclooxygenase and anti-inflammatory activity." Proceedings of the National Academy of Sciences. 84(5), 1417-1420 (1987).
- Zander E and Weisman S. "Treatment of acne vulgaris with salicylic acid pads." Clinical Therapeutics.14(2), 247-253 (1992).
- Eady EA, et al. "The benefit of 2% salicylic acid lotion in acne a placebo-controlled study." Journal of Dermatological Treatment. 7(2), 93-96 (1996).
- Akarsu S, et al. "Efficacy of the addition of salicylic acid to clindamycin and benzoyl peroxide combination for acne vulgaris." The Journal of Dermatology. 39(5), 433-438 (2012).
- Zheng Y, et al. "Clinical evidence on the efficacy and safety of an antioxidant optimized 1.5% salicylic acid (SA) cream in the treatment of facial acne: an open, baseline controlled clinical study." Skin Research and Technology. 19(2), 125-130 (2013).
- Jabarah A, Leon TG, and Zlotogorski A. "Salicylate intoxication from topically applied salicylic acid." Journal of the European Academy of Dermatology and Venereology. 8(1), 41-42 (1997).
- Tsai J, et al. "Distribution of salicylic acid in human stratum corneum following topical application in vivo: a comparison of six different formulations." International Journal of Pharmaceutics.188(2), 145-153 (1999).
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