Most alcohol starts as a “neutral grain spirit”. This is created by mixing together various grains (i.e. barley, rye, corn, wheat) adding water, and heating the mixture to very specific temperatures.
It is said that the distilling process removes glutenous proteins, but I have found that many people with gluten intolerance/celiac still react strongly to hard liquors. Personally, I think its safe to stick with alcohol made from a unique base – such as potatoes, berries, agave, etc. This includes alcohols such as Chopin (potato vodka), Ciroc (grape), and any Tequila (Agave).
Always consult your gastroenterologist or dietitian when making these choices!