When you first start using tampons, it may be more comfortable to start with a light or regular tampon, which is more slender. Once inserted, a tampon should last for at least two hours without leaks. If you find you are leaking sooner than two hours, try a larger size. If you soak through super-plus or ultra-sized tampons repeatedly in under two hours, that is considered a very heavy flow and you should speak to your healthcare provider. Most women need different sizes for different days of their period, such as regular at the beginning and end of their period and super or super-plus on heavier flow days.