When travelling to countries that speak a different language than you, it can be hard to tell restaurants about your food allergies. Pictures can help you overcome that language barrier so you stay safe.
Amazon sells allergy translation cards like the one above for several languages. For frugal travellers, it's easy enough to whip up your own -- simply download an image of the food you can't eat and put a big red cross through it using a free photo editor, plus the phrase "food allergy" in the appropriate language.
Travel blog also suggests having photos of things on your phone or printed out. Naturally, this would work with things other than food allergies, such as signs of places you need to get to. Although there are other ways to get by in a foreign country when you don't speak the language, photos are universal and convey your needs quickly.