Salicylic acid, a dangerous ingredient?

Can salicylic acid irritate the skin?

The salicylic acid is recognized for its exfoliating and purifying action, but it is not free from irritation, especially during the first applications. In the earliest weeks of use, it is common to experience mild discomfort : tightness, redness, tingling, or itching. These effects, while unpleasant, are not necessarily concerning. They often signal the skin’s adaptation to this new active ingredient, which stimulates cell renewal and promotes the elimination of dead cells.

In individuals with sensitive skin, reactions to salicylic acid can be more pronounced.

In this case, it is advisable to reduce the frequency of application (for example, every other evening instead of nightly) or to apply the treatment between two layers of moisturizer. Generally, skin tolerance improves after a few weeks, but if it does not, it means your skin cannot tolerate the salicylic acid and you should discontinue use.

Beyond transient irritations, allergic reactions may also occur. A recent study conducted between 2020 and 2024 assessed the allergenic potential of salicylic acid through with patch tests performed on 489 patients. Of these, 21 showed a positive reaction, corresponding to a reaction rate of 4.3%. Interestingly, 5 patients also exhibited cross-reactivity with other salicylates, suggesting that salicylic acid may serve as a marker of allergy to this class of compounds. However, no cases of severe reaction were reported, and the results indicate that the 5% skin tests were generally well tolerated. These findings underscore that, even though salicylic acid can be responsible for allergic contact dermatitis, these instances involve only a minority of individuals.

As with any new active ingredient, before using a product containing salicylic acid, we recommend that you test your skin’s tolerance on a small area, such as the inside of your elbow.

4 minutes to understand your skin. Our dermatological diagnostic guides you toward the ideal skincare for your specific needs. Simple, quick, personalized.

Is salicylic acid incompatible with other active ingredients?

Salicylic acid can be combined with various active ingredients depending on the skin’s needs: hyaluronic acid, niacinamide, vitamin C... However, its potent exfoliating effect requires caution when combining it with other molecules that also have an irritating potential. This is not a strict contraindication, but rather a matter of the skin’s ability to tolerate the simultaneous use of multiple exfoliating or sensitizing actives.

The combinations to watch are mainly those involving AHA-type acids, such as glycolic acid, but also those with azelaic acid or even retinoids (tretinoin, retinol, adapalene). These combinations can be beneficial in the long term, especially for skin prone to acne or pigment irregularities, but they increase the risk of dryness, redness, and peeling if introduced abruptly. For this reason, it is recommended to alternate their use (for example, using salicylic acid one evening and retinol another).

The important thing is to listen to your skin: if it starts to exhibit irritation, it’s advisable to space out applications or increase hydration.

Salicylic acid: should it be avoided during pregnancy?

The use of salicylic acid during pregnancy raises numerous questions. According to the Scientific Committee on Consumer Safety (SCCS), its use is considered safe when it complies with the maximum concentrations specified by the European Cosmetics Regulation. Moreover, the Food and Drug Administration (FDA) classifies salicylic acid as a Category C drug for pregnancy.

Category	Definition
A	Controlled studies in pregnant women have shown no risk to the fetus during the first trimester (and no subsequent risk either).
B	Animal studies have not demonstrated any risk, but there are no controlled studies in pregnant women. Alternatively, animal studies have shown an adverse effect, but this has not been confirmed in humans.
C	Animal studies have shown an adverse effect on the fetus, and no controlled studies have been conducted in women. Use may be justified if the potential benefit outweighs the risk.
D	Positive evidence of risk to the fetus in humans exists, but use may be considered in serious or life-threatening situations where no other medication is available.
X	Studies in animal or human subjects have demonstrated fetal abnormalities or clearly established risks that outweigh any potential benefit. Use is contraindicated during pregnancy.

Medication categories according to the FDA pregnancy classification.

In practice, this corresponds to treatments that typically contain less than 2% salicylic acid, applied topically to small skin areas. Under these conditions, the risk of systemic absorption is very low, and experts believe it poses no particular risk to either the mother or the fetus. However, caution is still advised: application on large areas, under occlusion, or on damaged skin should be avoided, as these scenarios may increase skin penetration and thus entry into the bloodstream.

In contrast, dermatological peels with high concentrations (~20%) of salicylic acid performed in a clinical setting are not recommended during pregnancy.

Regarding breastfeeding, available data are still limited. However, clinical observations suggest that low-concentration topical use does not present a major risk, as absorption into systemic circulation remains minimal and unlikely to reach breast milk. As a precaution, it is still preferable to restrict application to limited areas and avoid any contact with the chest.

Is salicylic acid photosensitizing?

Currently available scientific data suggest that the salicylic acid could act as a photosensitizer in certain experimental conditions. Laboratory research has shown that this molecule can accelerate the formation of thymidine dimers — a UV-induced DNA alteration — when exposed to light in the 300–350 nm range. This suggests that salicylic acid may amplify certain effects of UV light on molecular structures.

However, these findings remain limited to laboratory settings and do not directly reflect human skin’s response. To date, no clinical study has demonstrated that topical salicylic acid increases photosensitivity or the risk of sunburn. Available research instead focuses on salicylic acid’s role in the protective or regulatory mechanisms of plants exposed to environmental stresses, rather than on any deleterious effects in humans.

In practice, dermatologists consider that salicylic acid is not classified among ingredients reputed to be photosensitizing, but the use of a daily sunscreen remains recommended when using it, because of its keratolytic effect that slightly thins the skin barrier.

Does salicylic acid act as an endocrine disruptor?

The salicylic acid has sometimes been suspected of having endocrine-disrupting potential, notably because it belongs to the salicylate family, which also includes acetylsalicylic acid, more commonly known as aspirin. In Europe, it is classified as a category 2 reproductive toxicant (CMR2), meaning it is suspected of being "toxic for reproduction," although this has not been proven. This classification of salicylic acid is based on indirect data and not on robust evidence related to cosmetic use.

In reality, regulatory bodies have already extensively assessed its safety. In 2018, the SCCS concluded that salicylic acid is safe at the concentrations permitted by cosmetic regulations. This conclusion was confirmed in more recent opinions, the latest in 2023, which again endorses its safe use. Concerns about its endocrine-disrupting potential mainly stem from studies conducted in vitro, that is, under artificial laboratory conditions. However, it is not uncommon for these laboratory results to fail to translate in vivo, as demonstrated, for example, by the case of soy, which contains molecules that mimic estrogens but do not induce pathologies in humans.

Thus, while it is important to keep abreast of scientific advances in this field, the data available to date do not support considering salicylic acid as an endocrine disruptor.