Wearing a menstrual cup shouldn’t be uncomfortable when it’s inserted properly. They come in different sizes, and the right size cup should feel snug without pain or discomfort. You may have to try a few to get the right fit. Smaller sizes are usually a good fit for people who are younger and people who have strong vaginal muscles or a low-sitting cervix. Larger sizes usually work best for people with heavier flows or people who have given birth vaginally.