DOWNSIZING - WHY IT'S IMPORTANT
Downsizing refers to switching jewellery in a piercing to a shorter post, once initial swelling has subsided.
Because of the way piercings heal, most require initial jewellery with a noticeable amount of extra room to allow the tissue to swell in the early phases of healing. This is crucial to avoid jewellery embedding in the skin.
However, once the initial stages have passed, this initial swelling will have gone away. This will reveal the initial extra room and results in the initial jewellery now being too long. Jewellery that is too long can snag easily and move around excessively, leading to irritation and renewed swelling. In oral piercings, excessively long jewellery can lead to damage to teeth, gums, and other oral structures (read more in Oral Piercing Risks). At this stage, it’s important to return to your piercer to have shorter jewellery installed to reduce these issues. The piercing is not healed enough to safely change your jewellery by yourself at this point in healing.
If this window for downsizing is missed for piercings such as the helix, the excessive length may lead to migration or a change of angle of piercing, especially if the piercing gets slept on. This damage is irreversible and can get bad enough to result in the piercing failing.
CREDIT - SAFEPIERCING.ORG