Browse the shelves of a pharmacy or natural grocery store and you’re likely to spot small bottles of fragrant oils, such as lavender and peppermint, extracted from plants. Known as essential oils, these are the tools for the practice of aromatherapy—applying oils to the skin, sniffing them, or heating them in a device called an essential oil diffuser that disperses them into the air. Aromatherapy products are also available as lotions and soaps.

Promoters of this complementary therapy say it can aid sleep, relieve migraines and nausea, improve emotional well-being, and more. And U.S. consumers are buying into it; they spent about $1 billion on essential oils last year alone, according to market research firm Spins.

Does aromatherapy work? Currently there is no proof that the practice can cure any illness. For many of the “softer” claims—such as its purported role as a sleep aid or pain reducer—there has been little testing, and the scientific research that has been conducted has generally yielded conflicting results.

But when we examined the studies and spoke with experts, we found several ­areas in which the research seemed intriguing. Here’s what you need to know about three key aromatherapy claims.

Lifts Your Mood

Lavender and lemon essential oils are in many of the aromatherapy products that are marketed as mood boosters, and some small studies support the notion that they (along with jasmine) may help—if only temporarily.

But recent research had mixed results. In a study published in the journal Psycho­neuro­endocrinology, researchers taped cotton balls scented with lavender oil, lemon oil, or distilled water to the noses of 56 volunteers and quizzed participants about their mood. “There were not significant positive effects for lavender, but the mood effects for lemon oil were notable,” says study lead Janice Kiecolt-Glaser, Ph.D., a psychiatry professor at Ohio State University.

Reduces Anxiety

You’re likely to see essential oils such as bergamot, chamomile, frankincense, lavender, lemon, and rose in aromatherapy products touted to relieve anxiety.

Some research suggests that the scents of lavender and lemon essential oil may be helpful, but the studies are specific to those with dementia. For example, a 2015 study of 186 dementia patients, published in the journal BMC Complementary and Alternative Medicine, found that lavender essential oil had calming effects, especially in combination with acupressure—the application of pressure to points on the body. In an earlier study of 71 people with dementia, published in the Journal of Clinical Psychiatry, lemon balm essential oil reduced signs of agitation, such as throwing objects or screaming.

Relieves Nausea

Ginger and peppermint essential oils are commonly sold as stomach soothers. Some studies suggest that they, along with cardamom or fennel, may reduce nausea. But the most compelling research is on isopropyl alcohol, according to a review of nine studies. And a study published in the Annals of Emergency Medicine found that nauseated hospital patients who sniffed alcohol swabs reported significantly less nausea than those who sniffed salt­water.

Isopropyl alcohol swabs are in most first aid kits and are inexpensive, so people can easily use them to alleviate nausea, says study author Antonia Helbling, M.D., an emergency medicine physician at San Antonio Military Medical Center.

So what do our experts think about scent as medicine?

“Using the smell of alcohol to help with nausea may seem promising, but there simply isn’t enough solid evidence to back up most of the health claims for essential oils,” says Consumer Reports’ chief medical adviser, Marvin M. Lipman, M.D. “And do not trust any aromatherapy product that claims to treat a specific illness.”