After spending weeks testing bidet seats, or washlets—devices that squirt water at your bottom after you poop—I came to one main conclusion. Using a bidet to rinse fecal matter off with water feels better and cleaner than using toilet paper. But is it actually healthier?

Companies that sell bidets certainly capitalize on the idea that it is. According to the copy on bidet retailer Tushy’s website, the device “helps prevent gross butt syndrome,” which encompases “hemorrhoids, UTIs, general germy stank.” Bidet.org has a blog entry with a laundry list of further ailments that the devices can help, and Brondell—maker of the bidet toilet seat that we recommend as a budget option—claims that bidets can prevent urinary tract infections.

I fact checked these claims with Dr. John Swartzberg, a clinical professor emeritus at the University of California, Berkeley, who evaluated the peer-reviewed literature on bidets for an article in the Berkeley Wellness Letter. (I asked him how many people come to him for medical advice on using a bidet. “You are the first person,” he said.) Although there is some support for some of the claims, ultimately, you likely shouldn’t turn to a bidet to improve medical issues.

It seems logical that a bidet would make you cleaner than toilet paper. They certainly made me feel cleaner. But there’s no hard evidence, no peer-reviewed papers, and nothing that proves bidets actually reduce the amount of fecal matter on your bottom better than toilet paper alone, or make it any less germy, according to Dr. Swartzberg. I personally found that how clean you get will vary based on whether you use it in combination with toilet paper—I found myself using a couple squares to get totally clean after rinsing off with a bidet. Never fear: Your butt is probably fine with whatever level of microbes and poop it’s sporting now. We do not have some national health crisis in America where our butts are too dirty. “General germy stank” is not a real health problem. (Tushy’s publicist declined my interview requests.)

Your butt is probably fine with whatever level of microbes and poop it’s sporting now.

What is a problem is itchy buttholes. An estimated 1 to 5 percent of the population has “pruritus ani,” as the condition is called scientifically. If you have this problem, your first course of action is to find out if there is an underlying disease causing the itching (“talk to your doctor” is going to be a theme in this post), and to treat that. If there’s no cause to be found, the recommendation (as spelled out in this paper) is to avoid anything that can irritate the anus, like toilet paper. Therefore, cleaning with water after pooping, whether from a bidet or not, is a good idea. “When a bidet is used, it is better to use warm water and relatively low water pressure to avoid irritation of the anus,” the authors of the paper write. They also suggest blow drying the area with a blow-dryer, rather than wiping off water with paper—bidets can help here, too, as many have fans to dry your bottom, though they are not as strong as a blow-dryer. (Using the air-dryer function also might blow microbes from your bottom into the air, adding to what’s known as the “fecal cloud.” That sounds gross, but it’s probably not bad for your health—every time you flush a toilet after pooping, small particles of fecal matter become airborne, and you’re doing fine.)

It’s possible that bidets can help alleviate other medical problems, such as anal fissures, hemorrhoids, or constipation, but again, there’s not a lot of data to support that. One small study found that using a bidet can reduce the “anorectal pressure.” Twenty participants had catheters inserted in their bottoms and spent a minute using the bidet, at various water pressures. The pressures that their rectums exerted on the catheter was lower when they used the bidet than when they did not. Lower anorectal pressure could in turn be beneficial for treating medical problems, says Dr. Swartzberg; although it’s important to remember that the effects of bidets on these issues has not been studied directly. Also, there’s at least one report that suggests a bidet could have been the cause of an anal fissure.

It’s also important to not use a bidet on too high of a water pressure setting. Many bidets—including our top pick—have a setting that is strong enough to penetrate the anus. That’s too much, say the authors of the paper on anorectal pressure. “A high-pressure water jet flow should be avoided as it causes reflex contractions of the anal sphincters and might damage the mucosa and anal sphincter in the long term.” Dr. Swartzberg put it in more plain terms: “This is a horrible idea.”

Many bidets have a setting that is strong enough to penetrate the anus. That’s too much.

So your butthole is likely just fine as it is, and your vagina—if you have one—probably is too. Most bidets come with a feminine wash function, which is designed to “clean” your vagina (the stream actually penetrates, which feels as weird as it sounds). Bottom line: You do not need to clean your vagina. Your vagina cleans itself. Cleaning your vagina with water alone is not as actively bad for you as using a douche with other things mixed in—very bad!—but that’s maybe the best thing that can be said about it. One study reports that regularly using the feminine wash feature can alter your microflora. Dr. Swartzberg says there’s no evidence that the microflora were altered in a significantly negative way in that study, but your vaginal microflora are probably just fine as they are. (If you are experiencing a weird smell or discharge, see your doctor.)

Cleaning around your urethra—which, based on the default position of the spray, doesn’t seem to be what the feminine wash feature is meant for—isn’t necessary, either. Manufacturers sometimes claim that bidets can help reduce urinary tract infections. Dr. Swartzberg says that there’s just no data that he knows of to support that, and in fact, it’s possible that the warm water might irritate the urethra if squirted directly at it. Still, when I tested bidets in my apartment, my roommates reported liking the feminine wash feature. Use it if you want. Just be aware of the health unknowns involved.

Using a bidet poses another potential danger: They are squirting hot water at sensitive areas. One report describes “a case of scald burn in the perianal region caused by using the bidet.” You’ll probably be fine. The bidets we tested will heat cold water so it’s warm, but not hot enough to burn—the highest temperature we measured was 99 degrees Fahrenheit. Exercise caution when you first install the bidet; though, unless it’s defective, this risk seems pretty unlikely.

If you (or an adult in your care) have trouble wiping, using a bidet might be a big help in assisting with the cleaning task. The key word is “might.” In a study of 22 nursing-home residents, half reported that the bidet had “a positive effect on toileting.” However, “nursing staff reported that the toilet functions did clean the residents, but that cleaning was not complete.” Whether a bidet will be useful for someone in a nursing home or aging in place really depends on their personal circumstances and preferences.

Dr. Swartzberg suggests there’s a practical reason for the lack of scientific studies on bidets. Medical studies need a control group to prove the treatment itself makes people better, and not the mere theater of treatment—one group receives a sugar pill, instead of the real drug; one group is put under and cut open, but no device is implanted. With bidets, there’s no way to convince someone that a device is shooting water at their bottom without actually doing it.

Dr. Swartzberg’s bottom line: “Use it if you want to. Make sure the water is not too hot.” If you have hemorrhoids or fissures—say it with me: Check in with your physician! They’ll help you monitor the condition to see if the bidet is making things worse.