How often should you change period underwear?

It depends on your flow and the absorbency. On light days a pair can last most of the day; on heavy days, change every few hours, just as you would a pad. Overnight styles are designed to last a full night's sleep.

A good rule is to change when the underwear feels full or you no longer feel dry. Keeping a spare pair in a discreet wash bag makes changing on the go easy.