Using mouthwash twice or more a day may keep your breath “minty fresh,” but it also may increase your risk of developing type 2 diabetes.

A recent study observed 945 adults for three years. The people studied, ages 40 to 65, were overweight or obese, so they already were at increased risk for diabetes—but the results may be important even for people who are not overweight. Findings: Participants who used a mouthwash twice or more a day typically had 55% higher risk for prediabetes or diabetes than those who used mouthwash less frequently or not at all.

This kind of study can’t show cause and effect, and it leaves many questions open—especially about the kind of mouthwash people used. But there are reasons to avoid excessive use. Most mouthwashes contain alcohol or other ingredients, either synthetic or ­essential oils, that kill microbes ­indiscriminately—including beneficial ones that help the body make nitric oxide. But you need nitric oxide—it’s a remarkable compound that is important for everyone’s health, protecting against not only obesity and insulin resistance but also high blood pressure.

The truth is, you don’t need to use mouthwash at all. It’s not particularly effective at improving oral health anyway. For example, brushing and flossing are much better at disrupting plaque, the biofilm that sticks to teeth and causes cavities, gum disease—and, often, bad breath. Tip: Thin, unwaxed floss is best at physically dislodging plaque. (If you still love the mouthwash habit, choose alcohol-free products to avoid drying the delicate mucous membranes of the mouth.)

Finally, don’t ignore persistent bad breath. It could point to a health problem. If you are using mouthwash several times each day to get rid of bad breath or a bad taste, speak with your dentist or other health-care provider­.