When you’re faced with a tough cleaning job, it’s easy to get frustrated — and tempting to get creative with how you combat it. But before you reach for every cleaning product under your sink and start playing chemist, please just don’t.

“People often think that if one product works, mixing it with another one will make it even better,” says Carolyn Forte, director of the Cleaning Lab at the Good Housekeeping Institute
But here’s the scary truth: “Certain products, which are safe when used alone, can sometimes cause unsafe fumes or other chemical reactions when mixed with other products,” says Nancy Bock, Senior VP of Education at the American Cleaning Institute
And even if your ad-hoc cleaner combo isn’t dangerous or toxic, you can never be sure what effect two products can have on a surface or fabric when combined. Always read the warning and ingredient labels on cleaning products — and nevermix these:

1. Drain cleaner + drain cleaner

Katja Cho

“I would never recommend mixing two different drain cleaners or even using one right after the other,” says Forte. “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. Instead, call a plumber, Forte says.

2. Baking soda + vinegar

Katja Cho

We’re calling you out, Pinterest: Although these pantry staples are handy on their own (both baking soda and vinegar can help clean all over the house), skip any DIY cleaner recipe that involves this not-so-dynamic duo.

“Baking soda is basic and vinegar is acidic,” says Bock, “When you put them together you get mostly water and sodium acetate. But really, just mostly water.” Plus, vinegar causes baking soda to foam up; if stored in a closed container, the mixture can explode.

3. Hydrogen peroxide + vinegar

You may have heard that you should spray fruits or countertops with alternating mists of hydrogen peroxide and vinegar, wiping down the surface between sprays. Experts say this method is safe — but don’t 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.

4. Bleach + vinegar

[Good House Keeping]