<<Disclaimer:  Verify this information before applying it to your situation.>>

Kombucha tea is made up of a complex mixture of fungi and
bacteria.  While the primary fungal component is probably
constant from batch to batch, there is no way to prevent other
microrganisms from growing with the fungus and contamination
from airborn sources can happen easily.  Thus, you really don't
know what you are drinking in terms of microorganisms.  It's
probably safe for celiacs as long as the medium you use to grow
it contains no gluten.  If you are allergic to molds or yeasts,
I would avoid this.
Karen Hughes
Dept of Botany, Univ. Tennessee