The Rule
Before receiving Holy Communion, you must fast for one hour. That means no food and no drink — except water and medicine — for one hour before you receive the Eucharist.
Not one hour before Mass begins. One hour before you actually receive Communion. Since Communion typically happens about forty-five minutes into Mass, this means that in practice, you need to stop eating about fifteen minutes before Mass starts.
Water can be taken at any time, right up to the moment of Communion. Medicine — whether prescription or over-the-counter — can also be taken at any time without breaking the fast, regardless of whether it is in liquid, tablet, or any other form.
That is the entire rule. It is simpler than most people think.
What Counts as Breaking the Fast
Food of any kind breaks the fast. A biscuit, a sweet, a piece of chewing gum — all of these count.
Drinks other than water break the fast. Tea, coffee, juice, milk, soft drinks — all count. Some people wonder about flavoured water or water with a slice of lemon. Strictly speaking, plain water is what is permitted, but a slice of lemon in water is not the kind of thing the Church intends to legislate about. Use common sense.
Toothpaste does not break the fast, provided you do not swallow it. Brushing your teeth before Mass is fine.
Chewing gum does break the fast, because it is a food product being consumed, even if you do not swallow it. Finish your gum before the one-hour window.
Who Is Exempt
The elderly and those who are ill — even with a minor illness — are exempt from the Eucharistic fast. So are their carers, if fasting would prevent them from attending to the person in their care.
If you have a medical condition that requires you to eat regularly — diabetes, for example — you are exempt. You should receive Communion without anxiety. The Church does not ask you to endanger your health.
Priests who celebrate more than one Mass on the same day are permitted to eat and drink between Masses, even if the one-hour fast is not observed before the second or third Mass.
How It Used to Be
The current one-hour fast dates from 1964, when Pope Paul VI reduced it from three hours. Before 1957, the fast was from midnight — meaning no food or drink of any kind from midnight until you received Communion, however late in the morning Mass was celebrated.
For centuries before that, the fast was even stricter. Water was not permitted. The faithful went to Communion having consumed nothing at all since the previous evening. This was the practice for most of Catholic history.
The relaxation was pastoral. The Church recognised that a strict fast was discouraging some people — especially those attending later Masses, the elderly, and working people — from receiving Communion at all. The shorter fast removed the obstacle while preserving the principle.
Why the Church Asks This
The Eucharistic fast is small — one hour, water permitted, medicine exempt — but it serves a real purpose.
It is a bodily act of preparation. Just as you might dress carefully for an important occasion or arrive early for a meeting that matters, the fast is a way of telling your body what your soul already knows: something extraordinary is about to happen. You are about to receive the Body and Blood of Jesus Christ. The brief hunger reminds you that this is not ordinary eating. It sets the Eucharist apart from every other meal.
It is also an act of reverence. The ancient Christians fasted from midnight because they believed — as the Church still teaches — that the Eucharist is the most sacred reality on earth. A one-hour fast is a modest echo of that reverence. It costs you almost nothing. But it means something.
If You Forget
If you accidentally eat something within the hour — you absent-mindedly grab a biscuit, or you lose track of time — do not panic. If it was genuinely accidental and you realise it only as Communion approaches, most moral theologians would say you may still receive. The obligation is a matter of reverence, not a trap. God knows the difference between carelessness and contempt.
If you deliberately disregard the fast — eating a full meal thirty minutes before Mass with no concern for the rule — that is a different matter. It reflects a lack of reverence that the fast exists to cultivate.
When in doubt, receive. The Eucharist is food for the journey, and Christ does not want you to stay away over an honest mistake.