Mustum and wine only
Some people cannot receive under the species of bread at all. Some priests also have medical needs. This page defines terms and shows the practical steps that avoid cross contact.
What mustum means
Mustum is grape juice that has begun to ferment but has been suspended before fermentation is complete. It contains minimal alcohol. The Church permits its use for priests and laypeople who cannot consume alcohol for medical reasons.
How a separate chalice works
If you receive under the species of wine only, a separate chalice must be prepared to avoid cross contact from intinction (when others dip hosts into the wine). The celebrant should consecrate this chalice separately or ensure no contaminated hosts touch it.
How to avoid commingling cross contact
During the fraction rite, a small piece of the host is placed into the chalice. If you're receiving from a separate chalice, this should be done with a different portion, or your chalice should be set aside before this rite.
When to talk to your pastor
If you need to receive under the species of wine only, schedule a conversation with your pastor before your first Communion in this manner. Bring the parish conversation card if it helps. Most pastors are willing to accommodate—they just need to know the logistics.