Is there a difference between the two conditions?  Yes.  It can be difficult to determine whether one has an intolerance or an allergy because the signs and symptoms overlap.

A simple explanation of the two conditions –
Food allergy = immune system reaction to food
Food intolerance = inability to digest a food

Food allergy symptoms show up immediately whereas an intolerance may or may not manifest soon after ingesting the food.  In food allergy, the reaction can occur with smallest quantities but in food intolerance, the person is able to tolerate the food in small amounts or over a period of time. Food allergy can be life-threatening sometimes but not food intolerance.  A physician or an allergy specialist will be able to diagnose the problem.

Nuts, dairy, egg and fish are the most common food allergens.  Common food intolerance list includes wheat, gluten, milk, yeast, food additives and preservatives.

Symptoms of food allergy can vary from dizziness, swelling of lips and throat, itchy skin and red eyes, to nausea, diarrhea, vomiting, wheezing, shortness of breath, or blocked nose.  Food intolerance can show up as bloating, stomach discomfort, diarrhea, vomiting, headache, wheezing, hives or runny nose.

If you’re aware of the problem that you have, check labels when you buy packaged foods.  The best way to prevent such problems from occurring is to avoid the foods that cause these problems.  Maintaining a diary of the foods that you eat can help to trace the allergen or the food that causes the problem.