Many people confuse true food allergies and food intolerances. There are some similarities in symptoms, but true food allergies are more severe. In children, some of the most common foods that invoke food allergies are cows milk proteins, egg whites from hens, wheat, soy beans, peanuts, and codfish. Common food allergies in adults are a little bit different, and these include Brazil nuts, almonds, hazelnuts, peanuts, and walnuts. Other triggers for food allergies in adults can include fish, mussels, crab and shellfish, prawn, shrimp, and squid.

Localized oral food allergies can occur in adults in association with silver birch tree pollen. When a localized oral food allergy occurs, people can get an itchy mouth and throat from eating things like certain fresh fruits like peaches, cherries, and apples, and also from raw vegetables like carrots, potatoes, and also from nuts.

Usually, food allergies present themselves within a few minutes of eating an offending food by the onset of rashes, diarrhea, swelling of the lips and face, difficulty breathing, and in severe cases, someone with food allergies can go into anaphylactic shock. Delayed reactions to foods with food allergies can also occur, such as aggravated eczema and Celiac disease. Celiac disease looks like food allergies, and is a delayed immune reaction to the gluten part of wheat.

Unlike food allergies, food intolerance reactions are slower, do not involve the immune system, and are not usually life threatening. They are often referred to as pseudo allergic reactions. Lactose intolerance, for example, is not one of the food allergies, but is an inability to digest the cows milk sugar lactose. Lactose intolerance, unlike food allergies, does not cause rashes, hives, or lethargy.

A problem that is becoming more common today is that people are having reactions to the preservatives and additives in food, and these reactions may look like food allergies. Some of the additives that are known to cause reactions include sulphites, salicylate, MSG, caffeine, and tartrazine. These reactions are usually dose related, unlike true food allergies, in which a tiny amount can trigger life threatening reactions for some people. It is important to remember that when trying to decide if someone has true food allergies or food intolerances, food allergies involve the immune system, and food intolerance reactions do not.