- Chronic health issues, Lack of get-up-and-go, or just mostly not feeling like yourself are all routine symptoms of food intolerances. Intolerance to foods can produce a lot of different symptoms including irritable bowel syndrome, or IBS, headaches, fatigue, eczema and mood swings. Symptoms most of the time develop some time after you have eaten food and so it can be tough to find the food that's the problem without being tested.