Well, every time you order a meal you think that it doesn't contain gluten, you could say ”No tiene gluten ¿verdad?" So if she or he answers "no, no tiene" you could ask "¿Estás seguro? Porque mi amigo es completamente intolerante al gluten."

Hello Rebekah, there is a word that you can use and almost restaurants understand: celiaca. so you can say: soy celiaca o ¿tienen menú para celíacos?

also you could ask if the food contains "harina o granos de trigo". While what Dalia says is technically correct, I being a vegan (and lacto intolerant) have found that in many countries if you ask something in very technical terms, they tell "oh, no no no, of course it does not have it!" but if you then rephrase it and use more common words and ask again, they end up admitting that "ah, yes, that is in it". While there are many nice people in Spain, it does happen from time to time that the other person thinks that you are just being unreasonably difficult and they just wave it off and think that because they eat it and like it, then there is no reason for you to worry about it. PS. I read somewhere that gluten intolerance can be cross reactive with other foods. While this is not related to Spain or Castellano, your friends might also check if they are intolerant to other foods...

no food flour! no comida con harinas!

Hi Rebekah - I sympathise. I aam travelling to Japan with my celiac daughter soon, and it is a concern. There are many resources out there, including facebook groups for travellers to share info. Here is link http://www.celiactravel.com/cards/spanish/ to a card written in Spanish for use in restaurants. Personally I find the Japanese equivalent a bit long winded, but then I have enoigh Japanese to give my own shorter explanation. But for people who have little or none of the local language, these cards are very useful.