Zinc PCA: what should you know about this ally for blemish‑prone skin?

Zinc PCA is a cosmetic active ingredient resulting from the combination of two compounds : zinc, a trace element naturally present in the body, and PCA (pyrrolidone carboxylic acid), an amino-acid derivative that is also found in the skin under physiological conditions. More precisely, PCA is part of the natural moisturising factor (NMF), a group of molecules involved in maintaining hydration of the stratum corneum.

From a chemical perspective, zinc PCA corresponds to a salt formed between zinc and PCA, which makes it possible to combine these two entities within a single molecule. This form is particularly used in cosmetics, as it shows good affinity with the skin and can be easily incorporated into various formulations (serums, lotions, creams), while remaining stable in aqueous solution.

Zinc PCA is an active ingredient obtained through a chemical synthesis process.

Zinc PCA is the result of a chemical reaction between pyrrolidone carboxylic acid and a zinc salt, most often zinc in the form of zinc oxide or zinc sulphate. PCA itself is obtained by the cyclisation of glutamic acid, an amino acid that occurs naturally in the body and is frequently derived from plant-based resources, such as fermented sugar. During the reaction, the acidic group of PCA binds to the zinc ion to form a stable salt, known as zinc PCA. This form makes it possible to combine zinc with an organic molecule that is already recognised by the skin.

The resulting form of zinc is stable and well tolerated by the skin.

Zinc PCA is primarily used to support blemish‑prone skin. Several studies have highlighted its effects on the mechanisms involved in acne, particularly inflammation and bacterial proliferation. In a clinical study conducted on 16 volunteers with mild acne, a formulation containing 1% zinc PCA combined with derivatives of vitamins B3 and B6 was applied twice daily for six weeks. The results showed a 60% reduction in inflammatory lesions, as well as a decrease in the production of porphyrins, compounds associated with the activity of Cutibacterium acnes, a bacterium involved in the inflammation of acne lesions. Notably, this improvement was accompanied by good skin tolerance, with no impairment of the barrier function, which is often a concern with anti‑acne treatments.

Moreover, zinc PCA also appears to play a role in processes related to photoageing, a term that refers to premature skin ageing caused by UV radiation. An in vitro study conducted on human dermal fibroblasts showed that zinc PCA was able to reduce the activation of certain transcription factors (AP-1) induced by UVA, leading to a decrease in the production of MMP-1, an enzyme involved in the degradation of collagen. At the same time, an increase in the expression of the vitamin C transporter (SVCT2) was observed, which resulted in a stimulation of type I collagen synthesis. These findings suggest that zinc PCA may help to preserve the structure of the dermis .

Finally, zinc PCA more broadly helps to protect the skin against oxidative stress. It acts as a cofactor for several antioxidant enzymes, in particular superoxide dismutase, which neutralises reactive oxygen species before they damage membrane lipids, proteins or DNA. Zinc PCA also helps stabilise cell membranes and limit lipid peroxidation, a process involved in the impairment of the skin barrier. At the same time, it takes part in regulating certain inflammatory pathways, notably by modulating the activation of transcription factors such as NF-κB, which helps to reduce the production of pro-inflammatory mediators and thus soothe skin irritation and redness.

The properties of zinc PCA for the skin, as previously described, are also of interest at the level of the scalp. The latter can likewise be affected by problems such as excessive sebum production, inflammation, or microbial proliferation, all of which are processes on which zinc PCA can act.

Furthermore, more specifically, zinc PCA is often used as an adjuvant in anti-dandruff treatments. As a reminder, dandruff is often associated with excessive production of sebum combined with a dysbiosis of the scalp, particularly linked to the fungus Malassezia. In a clinical study conducted on 20 patients with moderate to severe seborrhoeic dermatitis, the use for four weeks of a gel containing zinc PCA, in combination with salicylic acid and piroctone olamine, followed by a lotion containing salicylic acid and piroctone olamine, made it possible to significantly reduce dandruff, itching and erythema.

Another study confirms these positive results. Conducted on 30 patients, it evaluated a shampoo combining zinc PCA, piroctone olamine and plant extracts, including rosemary, chamomile, nettle and mint. The findings show a rapid disappearance of dandruff in some of the participants from as early as two weeks, and a progressive improvement in the others within four weeks

However, in both of these studies, zinc PCA is systematically used in combination with other active ingredients recognised for their anti-dandruff efficacy, which makes it difficult to assess its specific contribution.

In a different context, some data suggest a potential interest in zinc PCA for combating hair loss. A clinical study conducted on 19 men with androgenetic alopecia evaluated the efficacy of a topical solution containing caffeine, Procapil and zinc PCA over a 12‑week period. The results showed a 26.9% reduction in hair loss, as well as a visible improvement in hair density in approximately 68% of participants after twelve weeks.

Nevertheless, here again, zinc PCA is included within a combined formulation, which does not allow us to draw conclusions about its specific role in hair growth. These results nevertheless suggest that, when associated with certain active ingredients, zinc PCA could help to improve the scalp environment and support hair growth.

Zinc PCA is an active ingredient that is generally well tolerated.

Several clinical trials available in the scientific literature have included it in formulations intended for blemish-prone skin or scalps subject to imbalance, without reporting any undesirable reactions such as irritation or contact allergies. Unlike certain active ingredients used in the management of blemishes, such as retinoids or benzoyl peroxide, which are often associated with irritation, flaking or dryness, zinc PCA does not present these drawbacks. PCA plays a key role here by helping to maintain hydration of the stratum corneum, which makes it possible to counteract any potential drying effects of zinc alone.

In practice, zinc PCA can be used on all skin types, including the most sensitive, without any specific contraindications when applied topically. It is also suitable for use by pregnant women, making it a versatile active ingredient that can be easily incorporated into a skincare routine.

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• SHARIFI-RAD J. & al. Preparation of strong antidandruff shampoo using medicinal plant extracts: A clinical trial and chronic dandruff treatment. Jundishapur Journal of Natural Pharmaceutical Products (2015).

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