Winter means that we’re in the midst of cold and flu season. When everyone around us is sick, we tend to pay extra attention to hand washing and disinfecting household surfaces. However, if you feel like you’re always getting sick for no apparent reason, the answer might be lying in your travel mug.

Veronica Lucas took to Facebook to explain that some people are struggling to fight off colds and the flu, even after multiple rounds of antibiotics. If this sounds like you, your sickness may be the result of your travel mug or cup (like a Yeti, for instance).

Pick up the lid of your travel mug. You’ll notice that there is likely a rubber seal around the outside of the lid. These rubber seals are actually removable, and should be cleaned after each use. Otherwise, moisture and bacteria get trapped underneath them, and this creates the perfect breeding ground for mold and other sickness-causing germs. Yuck!

The best place to wash your travel mug is in the dishwasher on a hot water setting. If you don’t have a dishwasher, take apart and soak each part of your travel mug in hot, soapy water before washing as you normally would. Now that you know this gross (but important) information, hopefully you’ll lessen your chances of getting sick this winter!