These terms are often used interchangeably, despite the fact that they are medically quite distinct. For instance, someone who is lactose intolerant has a different set of symptoms than someone who is allergic to dairy.
A food intolerance occurs when your stomach cannot process a certain food properly or the body lacks the enzymes needed to digest it. A food intolerance can cause bloating, headaches, heartburn, gas, general discomfort or irritability, but it isn’t life-threatening.
Individuals with a food intolerance can also usually eat small quantities of the offending substance with little or no symptoms. Over time, this can still have serious consequences. For instance, those who suffer from Celiac disease, or gluten intolerance, can suffer serious long-term side effects from being unable to break down the proteins found in wheat and many other grains.
A true allergic reaction, however, can be triggered by even the tiniest amount of a substance and can induce rashes, hives, difficult breathing, tummy pain, vomiting and in some cases, anaphylactic shock.
Finally, some individuals are sensitive to certain food additives or chemicals, including sulfites (found in wine and preservatives), artificial colorings (particularly Red #40), artificial sweeteners and monosodium glutamate. This is in no way the same as an allergy, and the validity of some of these sensitivity claims is still under debate. If you or your child experience any discomfort after eating such additives you may avoid them to be on the safe side, but know that they do not represent a serious health threat.

