Squalane, a comedogenic ingredient?

The key points to remember.

Squalane is a stable derivative of squalene, naturally present in human sebum, which provides it with excellent biocompatibility and nourishing properties.
Despite its greasy texture, squalane is not comedogenic, unlike oxidised squalene.
However, studies on the comedogenicity of squalane have been carried out using animal models, which may limit the generalisability of the findings.
The individual tolerance is important in the concept of comedogenicity: an active ingredient may suit some and trigger comedones in others.

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What should you know about squalane?

The squalane is a lipid derived from squalene, a molecule naturally present in human sebum. Squalene contributes to the skin's hydration and protection, but it is chemically unstable because it contains several double bonds that make it prone to oxidation. To stabilise it, chemists hydrogenate these double bonds, producing squalane, a saturated form that is more resistant to air and light. Highly stable, the squalane still retains a chemical structure similar to that of the skin's own squalene and is characterised by an excellent skin tolerance.

Emollient and nourishing, squalane helps to strengthen the hydrolipidic film and maintain the skin barrier. By reducing transepidermal water loss and improving the cohesion of the stratum corneum, it promotes more supple skin that is better protected against external aggressors. Studies also suggest that squalane may contribute to slowing skin ageing and enhancing the penetration of other active ingredients into the skin, although these effects still require confirmation through further research.

Structures chimiques du squalane et du squalène. — Chemical structures of squalane and squalene.
Source: PubChem.

Squalane, responsible for the formation of comedones?

The squalane has an oily and nourishing texture, similar to that of vegetable oils. This very richness often leads to questions over its compatibility with oily or acne-prone skin. Yet squalane does not seem to clog the pores, nor encourage comedone formation.

Several studies have shown that squalane is non-comedogenic, unlike squalene, whose unsaturated structure renders it prone to oxidation.

Indeed, it is the oxidation products of squalene, known as squalene peroxides, that have a proven comedogenic potential and contribute to the inflammation observed in acne-prone skin. An experimental study specifically compared the comedogenicity of six lipid substances, including squalene and squalane, on the ventral skin of rabbit ears, a model frequently used to assess the comedogenic potential of cosmetic actives. The researchers evaluated both the effects before and after UVA irradiation, as well as the rate of lipid peroxidation.

The results showed that UVA-irradiated squalene became highly comedogenic, with extensive comedo formation associated with follicular hyperplasia and hyperkeratosis, whilst squalane, even when exposed to UVA, did not induce any comedonal lesions. Moreover, the lipid peroxidation rate was markedly increased for squalene but remained unchanged for squalane, confirming the latter’s chemical stability. This stability explains why squalane is not prone to oxidation and does not generate irritating, comedogenic peroxides. The study thus demonstrates that only unsaturated lipids, such as squalene or oleic acid, become comedogenic upon oxidation, in contrast to saturated lipids like squalane.

Niveaux de peroxydation lipidique sans irradiation par UVA ou après 18h d'irradiation par UVA. — Lipid peroxidation levels in the absence of UVA irradiation or after 18 hours of UVA irradiation.
Source: MOTOYOSHI K. Enhanced comedo formation in rabbit ear skin by squalene and oleic acid peroxides. British Journal of Dermatology (1983).

However, this study presents certain limitations: it relies on an animal model (rabbit ear), which does not perfectly replicate human skin physiology, even though it remains a reference model in cosmetology for assessing comedogenicity. Moreover, comedogenicity is a complex concept to evaluate, as it depends heavily on individual skin types: an active compound may be perfectly tolerated by one person and induce comedones in another. That is why, even though squalane is not a priori non-comedogenic, it is recommended to introduce it on its own into one’s skincare routine. Thus, after several weeks of use, one can determine whether this treatment suits one’s skin without causing blemishes.