Planning to kiss, work closely with a colleague or need your breath fresh for any other reason? Keep this tidbit in mind: Research shows that during Week 1 (when you have your period) and Week 4 (your premenstrual week) of your monthly cycle, your mouth has a higher concentration of volatile sulfur compounds—the stinky stuff produced by microorganisms that give you bad breath. As the researchers explain it, you’re producing less saliva during these weeks due to low estrogen, which means your mouth is less effective at naturally washing away these foul-smelling substances.

Luckily, keeping your breath fresh is easy: Simply brush your teeth and tongue more often, floss regularly and use an alcohol-free mouth rinse (ones with alcohol lead to dryer conditions in your mouth, which can worsen the problem). If those aren’t handy, studies show that sipping unsweetened green tea or black tea can freshen breath by killing the microorganisms that cause a stench. And, even drinking plain ol’ tap water can help by rinsing away the malodorous compounds!