After the expiration date of the band-aid, it can no longer be used. The main component of a band-aid is benzalkonium bromide, but of course there are also other pharmaceutical ingredients, the main role of the disinfectant and antiseptic. Band-aids are generally applied to wounds on the fingers or other parts of the body to create an antibacterial and anti-inflammatory surface, and to isolate bacterial contamination. If the band-aid is expired, the expired band-aid may have bacteria attached to it, and if the dressing with bacteria attached to it is covered on the wound, it can lead to wound infection instead. After the infection, it may cause inflammation of the wound, which will not play a positive role, but will play a negative role. So you should use a band-aid within the shelf life for treatment.