What Is Benzalkonium Chloride, and Is It Safe for Daily Shoe Use?

By Sylke Bommel · Updated August 2026 · 6 min read

What Benzalkonium Chloride Actually Is

Benzalkonium chloride, often abbreviated BAC or BKC, is a quaternary ammonium compound, a class of cationic surfactants used for decades in healthcare and personal care products for their disinfectant properties.

It's a familiar ingredient in medicine, not a novel or unusual one: it's used in hand sanitizers, surgical scrubs, wound cleaning products, and hospital surface disinfectants, precisely because of its broad-spectrum activity against bacteria, fungi, and certain viruses.

How It Actually Kills Fungus and Bacteria

BAC works by adsorbing onto the outer membrane of microbial cells and disrupting their structural integrity, essentially breaking down the cell wall until the organism can no longer function.

This mechanism is why it's described as broad-spectrum: it doesn't target one specific type of organism the way some antibiotics do, but instead physically damages the cell membranes of bacteria, fungi, and enveloped viruses more generally.

Is It Safe?

Concentrations up to 0.1% are generally considered safe for human use, and BAC has a long track record in FDA-registered facilities and healthcare products at these concentrations.

Like most active disinfectant ingredients, it's formulated at low, tested concentrations, not used at industrial strength, which is the difference between a hospital hand sanitizer and an industrial cleaning product.

The Antimicrobial Resistance Question, Fairly Explained

Some research has raised questions about whether long-term, high-volume exposure to benzalkonium chloride, mostly studied in industrial, food-processing, and wastewater settings, could contribute to microbial resistance over time.

It's worth being upfront about this research existing, since good information means not glossing over legitimate scientific questions. That said, this research generally examines continuous, high-concentration industrial exposure over years, a very different context from occasional, low-concentration use on footwear at home.

Why It's Used on Shoes, Not Skin

Formulas built around BAC are typically designed for footwear and surfaces rather than direct application to skin, since skin-specific antifungal treatments use different, gentler active ingredients formulated for prolonged skin contact.

This is why Imperial Feet's Anti-Fungal Shoe & Sock Disinfectant Spray, which uses BAC alongside isopropyl alcohol, camphor, and zinc ricinoleate, is designed specifically for footwear, while Athlete's Foot Treatment, formulated with skin-friendly ingredients like aloe vera and chamomile, is the appropriate choice for direct skin application.

Using It Well

Spray the interior of shoes, allow to fully dry before wearing, and use in a ventilated space, since the formula also contains alcohol.

As with any disinfectant product, following the label's recommended frequency, rather than using it more often than needed, is a sensible general practice for any active ingredient.

Frequently Asked Questions

What is benzalkonium chloride used for?

It's a broad-spectrum disinfectant used in hand sanitizers, surgical scrubs, wound care products, and household and footwear disinfectants, valued for its ability to disrupt the cell membranes of bacteria, fungi, and some viruses.

Is benzalkonium chloride safe to use in shoes?

Concentrations up to 0.1%, which is the range used in personal care and disinfectant products, are generally considered safe for human use, and it has a long track record in FDA-registered healthcare and consumer products.

Can I spray benzalkonium chloride directly on my skin?

Footwear-formulated sprays containing BAC are designed for shoes and surfaces, not prolonged direct skin application; a skin-specific antifungal treatment formulated with gentler ingredients is the appropriate choice for direct skin use.

Does benzalkonium chloride cause antibiotic resistance?

Some research raises this question specifically around continuous, high-concentration industrial or wastewater exposure over years, a very different context from occasional, low-concentration use disinfecting shoes at home.

How is benzalkonium chloride different from alcohol-based disinfectants?

Both damage microbial cell structures, but BAC works by disrupting cell membranes through surfactant action while alcohol denatures proteins; formulas often combine both for broader, faster antimicrobial coverage.

Clinical Sources

1. Novo Nordisk Pharmatech. Benzalkonium Chloride (BKC) as a Disinfectant. Pharmaceutical-grade ingredient overview.
2. The Effectiveness of Benzalkonium Chloride as an Active Compound on Selected Foodborne Pathogens Biofilm. Hygiene. 2022;2(4):20.
3. Inhibition effect of benzalkonium chloride treatment on growth of common food contaminating fungal species. World J Microbiol Biotechnol. PMID: 23572782.
4. Impact of benzalkonium chloride, benzethonium chloride and chloroxylenol on bacterial antimicrobial resistance. J Appl Microbiol. 2022.

Related Reading

• How to Disinfect Shoes and Socks to Prevent Fungal Reinfection
• Can You Catch Toenail Fungus From a Family Member?
• Nail Health: How to Keep Your Toenails Strong and Healthy

Sylke Bommel

Owner, Imperial Feet — Third-Generation Foot Care

Sylke Bommel is the owner and third-generation leader of Imperial Feet, the Dutch professional foot care brand her grandfather founded in 2001. Raised in Aruba and based in Haarlem, just outside Amsterdam, she has led the brand's international expansion for over a decade, growing Imperial Feet from a single Dutch distributor to a professional range used by pedicurists, podiatrists, and pharmacies in more than 20 countries, including the United States.

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Editorial note: Sylke writes from the perspective of a foot care brand owner and formulator, not a medical practitioner. Content is educational and does not replace individual medical advice from a qualified foot care professional.