Some of the reactions associated with caffeine allergies include difficulty breathing, shock, tongue, and facial swelling. These reactions are different than those associated with consuming too much
caffeine which include jitters, headache, insomnia, and irritability. An uncommon component to caffeine that people experience adverse reactions to is tannins, but it does happen. Tannins are not only found in coffee and soda, but in chocolate and red wine as well.