How to Recognize and Manage Allergic Reactions Recognizing an Allergic Reaction Allergic reactions happen when a person’s immune system overreacts to something usually harmless, such as food, pollen, bug stings/bites, or medications. Although very common, allergic reactions can be fatal so it is important to recognize the spectrum of symptoms occurring during an allergic reaction, what to do before help arrives and how to prevent incidences in the future. Mild Allergic Reactions: Hives Itchy skin Red, itchy eyes Nasal congestion, runny nose Rashes Moderate to Severe Allergic Reactions: Swelling of the hands, feet, lips, face, or throat Nausea, vomiting, diarrhea, …