Are you feeling vaguely tired, anxious, maybe stressed? Don’t blame current events or the looming holiday season—your body’s stress response system is probably out of whack. At least, that’s what integrative medicine doctors across the country will tell you, and they’ll be happy to sell you some trendy cures, too—herbs they might refer to as “adaptogens.” Over at MindBodyGreen, functional medicine practitioner William Cole touts that adaptogens strengthen your nails, improve your complexion, balance your hormones, give you more energy, boost your sex drive, fight infections, sharpen your memory, ease depression, improve your blood sugar, reduce bloating and gas, and even fight cancer.

That all sounds great, but what are adaptogens, exactly, and do they really do all these things? Adaptogens are natural substances, typically derived from plants, that supposedly help the body counteract and adapt to stress. Sounds like a win-win, but when I dug into the research, I uncovered some problems: The science on adaptogens is still heavy on hope and light on evidence. And there are reasons to question whether chemicals that combat biological stress would be universally beneficial.

First things first: Medicines aren’t proven to work unless they’re backed by science.

As I’ve written before, it’s really, really crucial that potential new remedies be carefully studied in people before being touted and sold as medical treatments—that’s true of so-called “natural” remedies as well as synthetic drugs. Yet while dozens of adaptogens are being recommended by alternative doctors as safe and effective cures for common ailments—Cole mentions more than 20 in his MindBodyGreen article—very, very few studies on adaptogens have been published. Take the chaga mushroom, an adaptogen Cole says will “keep skin youthful.” I searched through the U.S. National Library of Medicine’s database of more than 27 million published study abstracts and couldn’t find a single study in which researchers gave chaga to human beings for any reason, let alone to determine if the fungus slows down aging in the skin.

Other recommended adaptogens have been studied in people but haven’t proven particularly effective. Take Panax (Asian) ginseng, which, according to functional medicine doctor Josh Axe, is “the most well-known adaptogen” and also “considered the most potent” for boosting mental performance and reducing stress. A recent systematic review published by the Cochrane Collaboration, a highly respected independent organization that gathers and summarizes healthcare-related research, concluded that “there is a lack of convincing evidence to show a cognitive enhancing effect of Panax ginseng in healthy participants.” Another recent paper reported that while more research should certainly be done on Panax ginseng, “there is no conclusive evidence supporting its use in the treatment of any particular disease.” For the adaptogen considered the most potent and famous, Dr. Axe, this is pretty disappointing.

Another trendy adaptogen is an herb called Rhodiola rosea—also known as golden root—which grows in cold, mountainous regions in North America, Europe, and Asia. It has an interesting back story: Russia spent years studying Rhodiola in the 1970s, hoping the herb would help Russian soldiers endure fatigue and cold. (Russia also apparently tested Rhodiola on their Olympic athletes. I guess it wasn’t as effective as steroids.) The problem is, most of these decades-old Russian studies weren’t carefully controlled; many aren’t even available today to read. And although a handful of more recent studies have been undertaken to evaluate whether Rhodiola combats fatigue, findings have been mixed, according to a 2012 systematic review. The studies have not been all that robust, either: Of the 10 randomized controlled clinical trials analyzed in the 2012 review, zero appeared to be compliant with international criteria for proper clinical trial reporting. Whoops.

Now, there are studies that support the idea that adaptogens affect the biological stress response. The thing is, most of these studies have involved exposing isolated human or animal cells to adaptogens in the lab, observing that doing so affects a biochemical pathway that is part of the cellular stress response or reduces the cells’ production of stress-related molecules. These kinds of lab findings are not evidence that adaptogens will ease your stress symptoms or make you feel energetic or cure what ails you. What happens to cells exposed to adaptogens in a petri dish has no bearing on how you’ll feel after you take an adaptogen pill.

Making matters worse, the underlying idea that we should quell the body’s innate stress response could be wrong—or at least over-simplified.

Adaptogens are touted as healthy because they dampen the body’s stress response—much as antioxidants have long been considered healthy because they reduce levels of so-called oxidative stress incited by damaging molecules called free radicals. (Interestingly, many adaptogens are antioxidants.) The assumption has long been that oxidative stress—much like any kind of stress—is categorically bad, therefore anything that counteracts it should be good. But recent research suggests that this simple narrative has flaws. Some animals produce exceptionally low levels of natural antioxidants and have high levels of oxidative stress throughout their bodies, yet live surprisingly long, disease-free lives. Researchers have even engineered animals to either vastly over- or under-produce antioxidant molecules; doing so hasn’t had the expected good or bad effects on their health.

Tinkering with the body’s stress response could incite cancer growth, too. It’s a counterintuitive idea, because oxidative stress, which is quelled by antioxidants, has long been thought to incite the types of genetic mutations that cause cancer. Yet several large clinical trials in people have shown that mega-doses of antioxidants actually induce cancer growth rather than curb it. Some researchers now propose that molecules that reduce cellular stress might preferentially protect cancer cells, which, if true, would certainly not be a good thing.

Look, I’m not saying that adaptogens cause cancer. But even if they do counteract the physiological effects of daily stress—and let’s remember, there isn’t much science to back up such an assertion—that doesn’t mean it would necessarily be a hand’s-down good thing.

Before you hop on the adaptogen bandwagon, get acquainted with the little we know about them—and the very much that we don’t.

Most doctors believe adaptogens are safe, and the studies that have been published don’t suggest that they pose serious risks. (Many studies have identified minor side effects, though, and I’ll point out that no long-term clinical studies have been done.) But we don’t have clear evidence yet that adaptogens actually improve well-being or cure ailments, and the mechanics of the body’s stress response system are still somewhat of a mystery. So until we know more, there’s little reason to fork out cash on herbs like Rhodiola and Panax ginseng. Wasting money can spark anxiety too—so perhaps not buying adaptogens will ease more stress than buying them.