Honesty before the chalice
The Eucharistic fast teaches reverence and self-control. Its purpose is honest preparation before the Holy Body and Precious Blood. If the fast was broken by accident, hiding it harms the conscience more than the accident itself.
If there is time, ask the priest quietly before Communion. If there is no time, remain in your place and speak with him afterward. Waiting one Sunday can itself become an act of reverence and obedience.
A contrite heart
A broken and a contrite heart, these, O God, You will not despise.
The Church’s discipline is meant to form repentance, not anxiety. Accidents should be met with contrition, truthfulness, and pastoral counsel. That kind of response keeps the fast connected to its purpose.
When health or medicine is involved
People with medication, diabetes, pregnancy, nursing, illness, or other health concerns should speak with the priest ahead of time. A clear blessing gives the person a faithful way to prepare without confusion each week.