Is there any theological reason for not drinking the communion wine? So, when serving communion, I notice that there is a significant number of people who will eat the bread, but not drink the wine. (Note, I'm not talking intinction here - rather they eat the bread, then get up before the chalice is offered.)

Is there any theology behind this, or is it just a general "ick" factor at potentially drinking out of the same cup?
There is, as far as I know, no theological reason for not partaking of the wine. However there are a number of practical ones, more than just 'ick':


If you are sick and do not wish to infect others, and communion is by common cup. This can normally be avoided by intinction, but if intinction is not practiced then some people will avoid the wine.
If you are an alcoholic, or are sworn to total abstinence, and alcoholic wine is being served