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This sort of hyper-vigilance probably isn’t for the reason you think, though. While most of the surfaces or appliances in your home quickly turn into breeding grounds for mold, bacteria, and other nasties if not cleaned regularly, that’s rarely the case for diffusers. “I’ve never heard of this happening,” says Kathi Keville, Director of the American Herb Association. “Essential oils are antimicrobial or antifungal in general, so they actually help prevent things like mold from growing.”
Learn how to make a simple, germ-fighting hand sanitizer with essential oils:
Science backs this up. Research looking at diffusers specifically is scarce, but countless studies have shown that many commonly used essential oils—like thyme, clove, rosemary, sandalwood, eucalyptus, and tea tree —are potent germ-fighters. In other words, they actually help keep your diffuser clean. (The one exception where mold might be an issue is if you let water stand in a diffuser for days or weeks after the essential oil has run out, say Behling and Keville.)
Related: The 5 Most Versatile Essential Oils You Can Own—And 5 You Can Skip
So…why worry about it then? The answer has little to do with preventing the risk of filling your indoor air with toxins. Instead, it’s about helping your diffuser function optimally. Oils—especially highly viscous ones like patchouli or vetiver—leave behind residues that can gum up diffusers so they don’t work as well, Keville says. Those leftover residues can also affect the scent—and efficacy—of the next oil you diffuse, Behlinger adds. If you’re diffusing lavender to relax, for instance, any leftover aroma from that energizing grapefruit you diffused earlier in the day might make it harder to chill out.
Related: Why You Need To Dilute Your Essential Oils With A Carrier Oil—Plus The 5 Best Ones To Buy
Cleaning doesn’t have to be a big deal though. After each time you use your diffuser, just use a microfiber cloth or a Q-tip to wipe away any excess oil or water, Behling recommends. Then once or twice a month, give the equipment a more thorough cleaning by wiping everything down with rubbing alcohol. Or just drop a teaspoon of white vinegar into the diffuser and let it run, Keville says. But maybe do it outside, unless you want your space to stink.