What is salicylic acid?

Salicylic acid is a substance that has keratolytic and antimicrobial properties. It is widely used in areas such as dermatology, because it is able to promote the desquamation of the skin and avoid contamination by opportunistic bacteria and fungi.

Further, It has the ability to regulate the oiliness of the skin and act as a potential anti-inflammatory. In this way, it is considered a substance of fundamental importance to improve the appearance of aged skin.

Where does salicylic acid come from?

The bark of the white willow, Salix alba, contains a substance known as salicin. That's where you get salicylic acid from. However, this hydroxy acid can be found in other plants such as birch and gaulteri leaves.

Salicylic acid, belonging to the group of analgesic, antipyretic and anti-inflammatory agents, It was first described in the 18th century by Richard Stone. This reverend observed that the infusions of the bark of the common white willow cured the fever.

In the year 1899, This substance was first synthesized and was used to replace quinine in the control of fever and pain orally. One of its metabolites was salicylic acid, with qualities for topical use.

Actions and effects of salicylic acid

Its effect on the skin may be related to its impact on the structure of the skin. Salicylic acid affects the cohesion between keratinocytes, a cell type, and their desquamation.

In this way, and as we have already mentioned, This acid acts as keratolytic (exfoliating) and antimicrobial, in concentrations of 5 to 10%. In addition, it has been attributed direct anti-inflammatory effect, although it has not yet been confirmed. At lower concentrations, between 1 and 3%, it acts as a keratoplastic.

Keratoplastic substances are those that favor the regeneration of the horny layer and normalize a defective keratinization. As for keratolytics, these are defined as substances capable of causing the cornea to fall or reduce its thickness.

On the other hand, it is important to mention that salicylic acid is fat-soluble, that is, that can mix and dissolve with existing fats in the epidermis and with the sebaceous material that is stuck in the follicles.

When introduced into these lipid areas of the skin, causes exfoliation and peeling from the same.

Read also: Natural care for dry skin


We can stand out 9 main indications for which this substance is used:

  • Keratolytic: in the mentioned concentrations, to treat vulgar, flat and plantar warts.
  • Keratoplastic: 0.5% at the edge of the unstressed ulcers.
  • Photodamage: to repair this situation it is used alone (in concentrations of 10 to 15% in ointment or creams) or together with AHA (alpha hydroxy acids) or retinoic acid. It is used to repair actinic keratosis and sunspots on the backs of the hands and forearms.
  • Photoprotector: It acts as a chemical filter.
  • Antifungal: favors the penetration of topical antifungal drugs by eliminating the stratum corneum.
  • Anesthetic: It has a certain anesthetic effect by intervening in the synthesis of prostaglandins, substances related to pain. For example, it is used to relieve pain in ulcerated aphthous ulcers.
  • Analgesic: Some salicylic acid derivatives are used to relieve pain in bursitis and muscle aches.
  • Antipruriginosis: relieves itching
  • Anti-inflammatory: As well as its analgesic and anesthetic effect, the anti-inflammatory effect derives from its ability to inhibit the synthesis of prostaglandins.

Adverse effects of salicylic acid

Like all medicines and chemicals, salicylic acid can also trigger a series of adverse effects, among which include, most frequently, the following:

  • Toxicity due to systemic absorption: when the substance passes into the blood, it can trigger some problems such as nausea and vomiting.
  • Antimitotic and teratogenic: that is, it affects the division of the cells and affects the fetus. Therefore, its use is not recommended in pregnant women.
  • Allergic reactions: its use is contraindicated in people allergic to this substance since it could cause serious complications.
  • Psychic disturbances: these side effects are less frequent.

You may also be interested in reading: How to deal with an anaphylactic shock


Salicylic acid continues in force with the traditional indications and other more innovative, with a good profile of efficacy and safety.