There is a lot of confusion between food allergies and food intolerance. That's because people who have an intolerance for milk-or specifically lactose in milk--for example, may have many of the same outward symptoms as someone who is allergic to milk. But they are distinctly different conditions. A food allergy is caused by an immune system over-reaction to a normally harmless substances such as pollen or milk. Food allergies affect about 5 percent of children and 4 percent of teens and adults.A food intolerance is a gastrointestinal reaction to something in the food that irritates the digestive system OR a food that cannot be digested because the digestive system lacks the necessary enzymes or other chemicals to properly break down the food. Many more people have food intolerances. Lactose intolerance is the most common, affecting about 10 percent of all Americans.Symptoms of a food allergy may include: Rash or hives, Nausea, Stomach pain, Diarrhea, Itchy skin, Shortness of breath, Chest pain, Swelling of the airways, Anaphylaxis-or shock. Symptoms of a food intolerance may include:Nausea, Stomach pain, Gas, cramps, or bloating,Vomiting, Heartburn, Diarrhea, Headaches. If you find that you get an upset stomach and other symptoms after eating, you should talk with your doctor and see an allergist to determine if you have an intolerance or an allergy. Avoiding the food is of course the most effective solution, but that can be difficult some times. And since food allergies can trigger life-threatening anaphylactic reactions that cause difficulty breathing and low blood pressure, you need to know your risks-and be prepared by always carrying an Epi-pen. An Epi-pen is a single shot of the adrenal hormone epinephrine and it stops the most dangerous symptoms until you can get medical attention. For more information on allergic reaction sand treatments, watch the other videos in this series.