Ever tried to pronounce Isothiazolinones, Methylisothiazolinone or Methylchloroisothiazolinone out loud? Yeah, they’re a mouthful. And while their names are tricky, what they do inside your cleaning products is even more concerning.
These tongue-twisting preservatives are hidden in everyday household cleaners, quietly extending shelf life—but at what cost?
If you want a healthier home with fewer harsh chemicals, let’s take a closer look at what isothiazolinones are, why they’re used, and how you can swap them for safer, all-natural alternatives.
What are isothiazolinones?
Isothiazolinones—including Methylisothiazolinone (MIT) and Methylchloroisothiazolinone (MCI)—are preservatives that keep bacteria, mould and fungi from growing in liquid-based cleaning and personal care products. Essentially, they act like tiny chemical bouncers, making sure unwanted microbes don’t contaminate the product.
Sounds good in theory, right? But here’s the issue: while these preservatives keep products shelf-stable, they may also cause skin irritation, allergies and even long-term health concerns. In fact, some countries have restricted or banned isothiazolinones in personal care products—yet, alarmingly, they’re still hanging out in the cleaning aisle of our supermarket shelves like an unwanted spill.
How do isothiazolinones work?
MIT and MCI work by breaking down the cell structures of bacteria and fungi—pretty effective, but not so friendly for human skin. Over time, people may develop contact dermatitis, which shows up as redness, itching and irritation. If you’ve ever had a reaction to a cleaning product but weren’t sure why, these preservatives could be why.
And while they’re tough on bacteria, they don’t just disappear when you rinse them away—more on that in a bit.
Common cleaning products that contain isothiazolinones
If you use standard cleaning products, there’s a good chance you’ve got isothiazolinones hanging out under your sink. You’ll often find them in:
- All-purpose cleaners
- Laundry detergents
- Dishwashing liquids
- Disinfectant sprays
- Fabric softeners
- Bathroom and glass cleaners
These products come into contact with your skin, your dishes, your clothes—basically, everything. And if your laundry detergent contains isothiazolinones (which most do), washing your clothes might only make the irritation worse.
Common side effects of isothiazolinones
Reactions from isothiazolinones, methylisothiazolinone or methylchloroisothiazolinone may vary from mild irritation to more severe allergic responses. Some of the most common side effects include:
- Skin irritation: redness, itching, and rashes are all possible side effects of isothiazolinones, especially with prolonged exposure.
- Allergic contact dermatitis: over time, repeated exposure may lead to an allergic reaction, making your skin extra sensitive to these preservatives.
- Respiratory issues: some people report breathing difficulties, especially when using spray cleaners containing these chemicals.
- Eye irritation: direct contact may cause stinging, watering or discomfort in the eyes.
If you’ve ever noticed skin reactions after using certain cleaners, then they likely contain a chemical on our harmful ingredient list.
How to avoid isothiazolinones in your home
Good news: ditching isothiazolinones is easier than you think. Step one? Check the ingredient labels. If you see Methylisothiazolinone (MIT) or Methylchloroisothiazolinone (MCI), it’s time to rethink your purchase.
Instead, opt for brands that use natural preservation methods like essential oils or plant-based alternatives. Plenty of eco-friendly cleaners get the job done without sneaky chemicals hiding in the fine print.
The environmental impact of isothiazolinones
You might not think about what happens to your cleaning products once they swirl down the drain, but the story doesn’t end there. When isothiazolinones enter waterways, they may linger, affecting aquatic ecosystems in ways we don’t always see. Even in small amounts, these preservatives are toxic to marine life, disrupting delicate balances in rivers and oceans.
And because they don’t break down easily, they tend to overstay their welcome in the environment. That means long after you’ve scrubbed your counters, these chemicals could still be floating around, causing unintended consequences for the planet. A clean home shouldn’t come at the cost of a polluted ecosystem.
What to use instead
There are plenty of natural, effective alternatives that don’t come with the same risks. Many eco-friendly brands use safer preservatives like:
- Essential oils (tea tree, lavender, and eucalyptus all have antibacterial properties)
- Vinegar and citrus extracts, which naturally help preserve and clean
- Sodium benzoate and potassium sorbate are food-safe preservatives that won’t harm you or the planet
These ingredients not only keep your home fresh and clean but also let you breathe a little easier—literally and figuratively.
Choosing the right cleaning products for your home
At the end of the day, your home should be a safe, healthy space—not a chemical experiment. Avoiding isothiazolinones is a small but impactful way to protect yourself, your family, and the environment.
When you’re shopping for household cleaners, check the label or online ingredients. Look for plant-based formulas, biodegradable ingredients, and brands that are transparent about what goes into their products.
A little awareness goes a long way in making your home a healthier, greener place! Shop our range of eco-friendly products today.