If swallowing a horse pill in hopes of avoiding nutritional deficiencies isn’t for you, it’s understandable to be curious about vitamin patches. These mini patches, sometimes called stickers, promise to deliver the nutrients you need after you slap them on your body.

Vitamin patches are popping up at huge retailers like Target and Amazon, suggesting they’re not going away anytime soon. But there’s not as much information out there about these products compared to their pill or powdered counterparts.

While doctors and dietitians say there’s potential value in using these in theorythey also have some concerns. Here’s why they’re not rushing to recommend vitamin patches.

What are vitamin patches, and how do they work?

Every vitamin patch is slightly different, but the concept behind them is all the same. These patches are usually waterproof and are stuck onto your body to infuse a specific nutrient or vitamin combination throughout the day. Some of those include vitamin B, vitamin D, and multivitamins. For most, you simply remove the patch at the end of the day and toss it.

“The idea is that nutrients move from the patch, across the skin barrier, and into circulation over time,” Scott Keatley, RD, co-founder of Keatley Medical Nutrition Therapy, tells SELF. The concept can be appealing if you hate swallowing pills. “Instead of taking a pill and having the vitamin absorbed through our intestines, the vitamin crosses the skin and is absorbed that way,” Jamie Alan, PhD, an associate professor of pharmacology and toxicology at Michigan State University, tells SELF.

The patches are activated by body temperature and moisture, explains Sandra Zhang, RDN, LDN, registered dietician nutritionist at the Frances Stern Nutrition Center at Tufts Medical Center. “Fat-soluble vitamins might cross the skin easier than water-soluble ones,” she tells SELF.

There’s limited information on their safety and efficacy.

That’s the big sticking point for experts. “There’s not a lot of data on them,” Howard Greller, MD, associate professor of emergency medicine and medical toxicology fellowship director at Rutgers University – New Jersey Poison Information and Education Service, tells SELF.

While the labels on many of these vitamin patches say they’re for kids aged 12 and up, some look like they’re intended for children given their fun, bright designs. That has the potential to be harmful, although the lack of data about how much of the vitamins get absorbed makes it hard to know for sure, Dr. Greller says.