Zinc in Cosmetics — PCA, Oxide and Pyrithione. Three Forms, Three Functions

Zinc — one element, many roles in skincare

When you spot “zinc” on a cosmetic's ingredient list, it's easy to assume it refers to a single ingredient. In reality, zinc appears in cosmetics in several very different forms, each one serving a distinct function. Understanding these differences lets you choose products that genuinely match your skin's specific needs.

In this guide we'll look at the three most important forms of zinc in skincare: zinc PCA (sebum control), zinc oxide (sun protection) and zinc pyrithione (dandruff control). Each deserves its own section, because their mechanisms of action and applications are fundamentally different.

Zinc PCA — sebum control

Zinc PCA (Zinc PCA on the INCI list) is the salt of zinc and pyrrolidone carboxylic acid (PCA). It's one of the most effective forms of zinc for regulating sebum production.

How does zinc PCA work?

• Inhibits 5-alpha-reductase activity — the enzyme that converts testosterone into dihydrotestosterone (DHT). DHT is one of the main triggers of sebum production.
• Regulates the sebaceous glands — it reduces excess sebum production without completely blocking the skin's natural moisturisation.
• Acts as an antibacterial — it curbs the growth of bacteria on the skin, which matters for oily, blemish-prone skin.
• An NMF component: PCA is a natural component of the skin's moisturising factor, so zinc PCA supports hydration at the same time.

Who is it for?

Zinc PCA is an excellent choice for people with oily and combination skin. It's used at concentrations of 0.1–1% in serums, mattifying creams and toners. Results are usually visible after 2–4 weeks of regular use.

Zinc Oxide — physical UV protection

Zinc oxide is one of the two widely used physical (mineral) filters — alongside titanium dioxide. It's regarded as one of the safest sun-protection ingredients available.

How does zinc oxide work?

• Reflects and scatters UV radiation — unlike chemical filters, which absorb UV and convert it into heat
• Broad-spectrum protection: zinc oxide protects against UVA and UVB, making it one of the few single ingredients that provides full-spectrum coverage
• Photostable: it doesn't break down when exposed to light, unlike some chemical filters

The controversy around zinc oxide

Zinc oxide has a few well-known drawbacks:

• White cast: traditional formulas leave a visible white film on the skin, which is especially problematic for deeper skin tones
• Nanoparticles: “nano” formulas reduce the white cast but raise questions about the safety of penetration — current research indicates that zinc oxide nanoparticles do not pass through healthy skin
• Less elegant texture: compared with chemical filters, formulas with zinc oxide can feel heavier and less cosmetically refined

Despite these limitations, zinc oxide remains the gold standard in sun protection for sensitive, reactive and allergy-prone skin. It's also reef-safe, which carries real environmental significance.

Zinc Pyrithione — fighting dandruff

Zinc pyrithione (Zinc Pyrithione, ZPT) is an ingredient with antifungal and antibacterial action, best known from anti-dandruff shampoos.

How does zinc pyrithione work?

• Inhibits the growth of the Malassezia fungus — the microorganism responsible for dandruff and seborrhoeic dermatitis
• Regulates skin renewal: it slows down the excessively fast cell turnover of the scalp that causes flaking
• Antibacterial action: a broad range of antimicrobial activity

Regulatory status — an important change

It's worth knowing that in 2022 the European Union banned the use of zinc pyrithione in cosmetics (Regulation 2021/1902), classifying it as a CMR category 1B substance (suspected reproductive toxicity). The ban took effect on 1 March 2022.

This means that zinc pyrithione should no longer appear in products sold within the EU. However, it's still permitted in many countries outside the EU (including the USA). Products imported from outside the EU may contain it — which is why checking the ingredient list matters so much.

Alternatives to zinc pyrithione in the EU

Following the ZPT ban, manufacturers of anti-dandruff shampoos have turned to alternatives:

• Piroctone Olamine: an effective and safe alternative
• Climbazole: antifungal action
• Ketoconazole: available in pharmacy preparations
• Salicylic acid: keratolytic action that supports dandruff treatment

Comparing the three forms of zinc

Other forms of zinc in cosmetics

Beyond the three main forms, zinc also appears as:

• Zinc Gluconate: soothing, used in after-sun preparations and for sensitive skin
• Zinc Sulfate: astringent, used in anti-acne preparations
• Zinc Stearate: a component of powders and mattifying products

Each of these forms plays a different role, which only confirms that “zinc” in cosmetics isn't a single ingredient but a whole family. You can read more about controversial ingredients in our article on parabens.

Summary

Zinc is a versatile element, but the key is understanding which form meets your needs. Zinc PCA mattifies oily skin, zinc oxide protects against the sun, and zinc pyrithione (outside the EU) helps with dandruff. Don't be swayed by sweeping statements — always check the specific INCI names in the PurScore ingredient database.