Can the same underwear be worn for a second day? The useful everyday answer is to choose a fresh pair daily when possible. NHS personal-hygiene guidance recommends this to help keep the genital area clean and dry, rather than treating the change of date as an automatic infection deadline.
Underwear sits close to skin and can collect moisture during the day. Dampness and tight clothing may contribute to irritation, so comfort matters alongside cleanliness. After exercise or heavy sweating, replacing a damp pair is a practical extension of the same principle.
There is no need for a dramatic warning about one isolated lapse. Make clean, dry underwear part of an ordinary routine, and pay attention to persistent irritation rather than assuming a clothing change explains every symptom. The basic advice is straightforward: fresh clothing and gentle care.
Sources: NHS Scotland: Personal hygiene