It's totally normal for a tampon to bleed through when it gets saturated with blood and needs to be changed. Generally, tampons should be changed every four-to-eight hours. If ya find that you need to change your tampon more frequently than that, it may be that you need a higher absorbency tampon. Tampon sizes refer to different absorbencies--light, regular and super. Are you using super? And it’s a good idea to use an underwear liner in addition to a tampon if you’re havin’ this problem—it can prevent any seepage through your clothes.

If you’ve already tried this, suggests Elizabeth Bobby, a nurse practitioner in OBGYN at About Women By Women, in Wellesley, Mass., “make sure that you’re pushing the tampon far enough into your vagina; when it’s correctly inserted, you won't see any cotton at your vaginal opening, you'll only see string. If you see only string, and the string is saturated with blood, you need to change your tampon.”