Essential oils often evoke thoughts of scented candles and day spas, but their benefits beyond relaxation are less well-known.

Essential oils are ultimately just plant extracts — and those are used in countless cleaning and personal–careproducts, and are the main ingredient in some pest-control products and some over-the-counter medications, like Vick’s VapoRub and some lice sprays.

They’re used in the food industry because of their preservative potency against food-borne pathogens — thanks to their antimicrobial, antibacterial, and antifungal properties.

Various oils have also been shown to effectively treat a wide range of common health issues such as nausea and migraines, and a rapidly growing body of research is finding that they are powerful enough to kill human cancer cells of the breast, colon, mouth, skin, and more.

A handful of promising, real-life studies have been conducted with humans and other animals, though most of the research in that realm thus far has been conducted in the lab. More controlled trials will be required before some of these applications  will be available to the public, but meanwhile, scientists have turned up exciting results in another area of use: countering the growing antibiotic-resistance crisis.

“The loss of antibiotics due to antimicrobial resistance is potentially one of the most important challenges the medical and animal-health communities will face in the 21st century,” says Dr. Cyril Gay, the senior national program leader at the United States Department of Agriculture’s (USDA) Agricultural Research Service.