Pyrithione Zinc in Dandruff Shampoos: Potential Side Effects and Risks

It’s in thousands of dandruff shampoos on the shelf—yet banned in Europe as a reproductive toxin. Pyrithione zinc might be doing more harm than good to your scalp (and beyond).

Despite the effectiveness of pyrithione zinc in managing dandruff, there are emerging concerns about its potential side effects and risks of long-term use.

In this blog, we'll explore the hidden risks of pyrithione zinc and what safer alternatives are available for keeping your scalp healthy and flake-free.

Table of Contents: 

• What is Pyrithione Zinc?
• The Health Problems and Risks Linked to Pyrithione Zinc
• The Risks of Long-Term Use and Resistance
• The Environmental Impact of Pyrithione Zinc
• Regulatory Bans & Restrictions of Pyrithione Zinc
• Consumer Concerns & Sentiment
• Alternatives to Pyrithione Zinc in Dandruff Shampoos
• A Zinc-Pyrithione-Free Alternative

What is Pyrithione Zinc?

Pyrithione zinc is a chemical commonly used to reduce the symptoms of seborrheic dermatitis and dandruff. It can also be utilized in the management of acne, eczema, and psoriasis.

Because of its antifungal and antimicrobial properties, it is widely incorporated into shampoos, creams, and face washes.

What is Pyrithione Zinc Used For?

As mentioned earlier, pyrithione zinc is primarily used in anti-dandruff shampoos to control scalp conditions like dandruff and seborrheic dermatitis. It targets Malassezia, a naturally occurring fungus that's linked to the development of these skin conditions.

Malassezia typically lives on your skin without causing any issues. However, an increase in its population can be problematic. When there's an overgrowth of Malassezia, you might develop seborrheic dermatitis or dandruff and experience symptoms such as itching and flaking.

Zinc pyrithione helps to control the population of Malassezia through the following mechanisms of action: [1]

• Disrupting the production of energy within the yeast cell

• Disrupting the yeast cell's ability to metabolize and process nutrients for use

This can inhibit the growth of the fungus and prevent it from proliferating. By controlling the growth of Malassezia, zinc pyrithione shampoo may help minimize scalp irritation, redness, and flaking.

Because of its effectiveness, pyrithione zinc is found in many well-known anti-dandruff shampoos. However, concerns about its long-term impact on health and the environment have led some consumers to seek safer alternatives.

The Health Problems and Risks Linked to Pyrithione Zinc

While pyrithione zinc is widely used for treating dandruff, emerging research suggests it might increase the risk of several health issues as follows:

Reproductive Toxicity Risk

Some research has flagged pyrithione zinc as a potential reproductive toxin, raising concerns about its impact on fertility and fetal development. The European Chemicals Agency (ECHA) has categorized it as toxic to reproduction, contributing to the ban on pyrithione zinc in the European Union [2].

That said, more recent studies suggest that the amount of zinc pyrithione in shampoos might not have that significant of an impact on fertility or the development of a fetus [3]. So, as of now, more in-depth research is still required to establish the long-term effects of zinc pyrithione on fertility and pregnancy.

Skin Irritation & Sensitization

Some people experience side effects with the topical use of pyrithione zinc. Some of these side effects include [4]

• Dryness or peeling of the skin

• Redness

• Burning or stinging

• Blistering

Not everyone will experience these side effects, but in rare cases, they do happen.

DNA Damage in Skin Cells

One research study has found that pyrithione zinc may trigger cellular stress and DNA damage in skin cells. This raises concerns about its long-term impact on scalp and skin health, particularly with frequent use [5].

Again, more studies will need to be conducted to establish whether or not zinc pyrithione is harmful to skin cells when used long-term.

Possible Hair Loss

Some users have reported hair loss and thinning with prolonged use of pyrithione zinc shampoos [6]. This hair loss is typically temporary.

The Risks of Long-Term Use and Resistance

While zinc pyrithione is effective in managing dandruff, concerns have been raised about its long-term effects.

As an antimicrobial agent, pyrithione zinc continuously targets the Malassezia fungus and other microorganisms on the scalp. It inhibits the growth of Malassezia, thus controlling its population and reducing symptoms of seborrheic dermatitis and dandruff.

However, long-term exposure may lead to adaptive resistance, where fungi and bacteria become less responsive to treatment. This could make dandruff harder to control over time and potentially shift the scalp's microbiome.

Currently, there are no significant reports on fungal resistance to zinc pyrithione. However, an increasing number of cases of resistance have been reported for another group of antifungals called azoles [7]. One example is ketoconazole, which is also commonly used to manage dandruff and seborrheic dermatitis.

It is possible for other antifungal agents to eventually end up down this route, especially with prolonged use. In the case of zinc pyrithione, long-term use may make it less effective against the Malassezia biofilm as the fungus adapts. This biofilm is the natural protective barrier that shields Malassezia from the effects of antifungal agents. 

While this risk may be concerning, it's important to note that more research is needed to fully understand the long-term effects of zinc pyrithione on microbial resistance and scalp health.

The Environmental Impact of Pyrithione Zinc

The usage of zinc pyrithione also has significant environmental impacts. As a common ingredient in anti-dandruff shampoos, it often gets washed down the drain, entering water systems and affecting aquatic life. This can lead to the following issues:

• Bioaccumulation in Waterways: This ingredient can only break down near the water's surface when exposed to sunlight. Thus, it has a low degradation rate and can persist and accumulate, especially in coastal waters and sediments. This may contribute to long-term contamination and harm to aquatic organisms [8].

• Toxicity to Aquatic Life: Research has shown that zinc pyrithione is highly toxic to various species of aquatic organisms, including fish, shrimp, sea urchins, plankton, algae, and crustaceans. Even low concentrations of zinc pyrithione can have toxic effects, posing a long-term threat to aquatic life and biodiversity [8].

• Environmental Hazard Classification: Due to its ecological effects, environmental agencies have labeled zinc pyrithione as very hazardous to the aquatic environment, both in the long term and short term [9]. This classification highlights its potential for widespread harm and underscores the need for stricter regulations.

Regulatory Bans & Restrictions of Pyrithione Zinc

In response to growing concerns about its health and environmental risks, zinc pyrithione has been banned or restricted in multiple regions. Certain regulatory agencies have determined that its risks outweigh its benefits, particularly given the availability of safer alternatives.

• Banned in over 25 Countries: In 2022, the European Union (EU) officially banned zinc pyrithione in all EU countries. It has been flagged as a potential reproductive toxin, leading to the banning of its use in cosmetic products [10].

• No Essential Need: Regulators concluded that zinc pyrithione is not an irreplaceable or essential ingredient in anti-dandruff products, as safer and equally effective alternatives are available. This made it easier for authorities to justify its ban [10].

As more research emerges, other countries may follow suit and restrict or ban zinc pyrithione to protect public health and the environment.

Consumer Concerns & Sentiment

With the growing awareness of choosing safe hair care products, many consumers have been reconsidering their use of zinc pyrithione shampoos, especially following its ban in the EU.

Beyond regulatory concerns, there are also anecdotal reports from users highlighting undesirable side effects they experienced from using shampoos containing this chemical. Some side effects that have been reported include increased dryness, brittle hair, excessive hair shedding, and symptoms of an allergic reaction, such as redness and itching.

As of now, more research is still needed to confirm the potential risks of zinc pyrithione on health. But like many other consumers, you may feel its risks outweigh the benefits. Or maybe you live in a country where this ingredient is banned, and you're looking for effective replacements.

The good news is that there are plenty of alternative ingredients and natural remedies that can help manage seborrheic dermatitis and dandruff effectively.

Alternatives to Pyrithione Zinc in Dandruff Shampoos

If you're interested in gentler alternatives, you may consider the following options for managing dandruff and seborrheic dermatitis:

• Natural Antifungal Ingredients: Dead sea salt, manuka honey, and apple cider vinegar are all natural ingredients with antifungal properties. You can mix any one of these ingredients with water and apply the solution to your scalp as a natural remedy to combat dandruff or seborrheic dermatitis.

• Antifungal Essential Oils: Essential oils are concentrated plant extracts, some of which have antimicrobial and antifungal properties. Tea tree oil, for example, has been shown to reduce scaling, greasy crusts, and inflammation, while peppermint oil can help with flaking, itching, and dandruff. It's also important to note that essential oils shouldn't be applied directly to the skin. Be sure to dilute the essential oil in water or a suitable carrier oil like MCT oil before application.

• Non-Medicated Options: Some people find relief from dandruff without using medicated shampoos. Gentle, sulfate-free shampoos can support the maintenance of a healthy scalp without harsh chemicals that can strip moisture and cause irritation. An example is the Scalp Therapy Shampoo, which helps clear the Malassezia fungus, reduce flakes and itching, and nourish the scalp and hair.

By choosing a safer, more natural approach, individuals can still effectively manage dandruff without exposing themselves to the possible long-term risks of using zinc pyrithione.

A Zinc-Pyrithione-Free Alternative

Zinc pyrithione shampoo can effectively reduce dandruff and flaking. However, there are still concerns about the long-term impact of this chemical on human health and the environment.

The good news is that there are many alternatives to zinc pyrithione, including natural remedies such as essential oils, apple cider vinegar, or manuka honey.

Another gentler alternative is the Scalp Therapy Shampoo. This shampoo works through a three-step process.

Firstly, it contains ingredients that help deactivate the Malassezia biofilm, which is its natural protective shield, making it more susceptible to antifungal agents. The next step is to clear away the fungus before nourishing the scalp and hair, which is the third and final step.

The Scalp Therapy Shampoo is free from parabens, harsh fragrances, and hard-to-pronounce chemicals, making it safe and gentle for your skin and hair.