11 Cleaning Products You Should Never, Ever Mix

When oil and water are combined, they repel one another, with a layer of oil sitting on top of the water — proof that some things just don’t mix. And while oil and water yields a rather innocent result, there are certain duos that can pose a serious threat to your health and the environment when mixed together, especially when it comes to cleaning products. Even if it isn't necessarily dangerous or toxic, you can never be sure what effect two products can have on a surface or fabric when combined.

We get it: When dirt and grime is as stubborn as can be, it’s tempting to do whatever you can to eradicate it. "People often think that if one product works, mixing it with another one will make it even better," says Carolyn Forté, executive director of the Good Housekeeping Institute Home Care & Cleaning Lab. But there are better ways to get tough jobs done — like using the most effective carpet cleaners, toilet cleaners and all-purpose sprays. So before you start to play chemist, consult this list of solutions, cleaning products and other household products our Lab pros say you should never combine.

Bleach and vinegar

The combination sounds like it'd be powerful, but the two should never be mixed. "Together, they produce chlorine gas, which even at low levels, can cause coughing, breathing problems and burning, watery eyes," says Forté.

Bleach and ammonia

When combined, bleach and ammonia produce a toxic gas called chloramine. "It causes the same symptoms as bleach and vinegar — along with shortness of breath and chest pain," says Forté. Heads up: Many glass and window cleaners contain ammonia, so never mix those with bleach.

Bleach and rubbing alcohol

You’ve likely heard of chloroform, and that’s exactly what bleach and rubbing alcohol make when mixed. The highly volatile compound that can cause coughing, breathing problems and eye irritation. And, yes, it can even be powerful enough to sedate when inhaled or ingested.

Bathroom cleaners and bleach

Have some stubborn mold and mildew in the bathroom? While it may be tempting to try these two powerful cleaners together to remove mildew, resist the urge. Many bathroom and toilet cleaners contain acids that can produce chlorine gas when combined with bleach. This can cause breathing problems and irritate the eyes and nose.

Rust removal products and bleach

​​The best rust removal products can get the job done without the help of bleach. Together, these solutions and sprays and bleach release irritating and toxic gasses.

Lemon and bleach

Lemon can be an effective household cleaning supply — use it to freshen your microwave or get stains out of a cutting board, for example — but it’s not a good companion for bleach since it’s acidic. Like commercial products that contain acid, the two can produce that toxic chlorine gas.

Oven cleaner and bleach

Oven cleaner is powerful enough, so don’t mix it with anything — not even the self-clean feature on your oven. Bleach and oven cleaner is another no-no, as it can produce chlorine gas. We already know this can cause coughing, breathing problems and eye irritation.

Drain cleaner and drain cleaner

"I would never recommend mixing two different drain cleaners or even using one right after the other," says Forté. "These are powerful formulas, and could even explode if combined." Use one product according to package directions (typically, only half a bottle is needed per treatment). If it doesn't work, don't try another product — call a plumber instead.

Hydrogen peroxide and vinegar

While these products can be used in tandem — for instance, you can clean countertops with alternating sprays of each, rinsing the surface in between — you should never mix the two products in the same container. Combining them creates peracetic acid, which is potentially toxic and can irritate the skin, eyes and respiratory system.

Baking soda and vinegar

This is one of the most popular DIY cleaning methods touted on social media, but our experts say to skip this “hack.” The two pantry staples are handy cleaning supplies on their own — baking soda is a mild abrasive for tough spots, like in a ceramic sink and vinegar can double as a great glass cleaner — but, contrary to popular belief, they don’t really work together. Because vinegar is acidic, and baking soda is basic, they basically just cancel each other out chemically, creating mostly water and some salt. The resulting bubbles may lift away enough to help lift some mess away or make a slow drain move again, but the mixture itself won't actually clean anything.

Vinegar and castile soap

This combo is another rather innocent yet highly ineffective one. When mixed, vinegar and castile soap don’t make a more productive cleaner — instead, the vinegar destabilizes the soap, turning it into a chunky and oily mixture that’s hard to work with.