There is no Church legislation that would prevent an alcoholic from receiving the precious blood at Mass, but it is extremely unwise for someone suffering from alcoholism to do so. After transubstantiation occurs, the eucharistic elements retain all the appearances of bread and wine; that is, they retain all the properties of bread and wine that are apparent to the human senses. If someone is allergic to wheat, consuming the host could cause him to become ill. If someone is addicted to alcohol, drinking the precious blood could trigger alcohol cravings.
It is also necessary to point out that Christ is fully present – body, blood, soul, and divinity – under the appearances of the bread and the wine. There is no need for you to receive from the chalice in order to make a complete Communion. You will receive Christ fully under the host alone.
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