Some food allergies and intolerances can be mild, while others are life-threatening. For example, foods like peanuts or shellfish can create an anaphylactic reaction in some people, causing their throat and airway to swell so they cannot breathe. This type of response can be fatal when not treated.
Anaphylaxis occurs quickly after ingesting the food, and the signs include swelling of the lips and face, difficulty breathing, hives, nausea, vomiting, visible distress, dizziness, faintness, and a rapid heartbeat. Symptoms may seem mild at first but can quickly escalate.
Treatment for severe food allergy is calling 911 and administering an auto-injector, like an Epi-Pen, to the victim's thigh. Victims should be transported to the emergency room by ambulance instead of by car because symptoms can quickly worsen, and emergency medical staff can provide treatment on the way.