There are a few major differences between intolerance and allergy which need to be noted. An intolerance or sensitivity to something is almost always less serious than an allergy. An allergic reaction can be severe, even life-threatening.

You have probably heard stories of someone with a peanut allergy ingesting some food with a very small amount of peanut oil or peanut byproduct in it, and then dying as a result.

That illustrates the severity of an allergy as opposed to an intolerance. Regarding food, an allergic reaction may cause you to have trouble breathing and even to lose consciousness. Typical intolerance reactions to some food item can be as simple as an upset stomach that only lasts a few minutes, or as serious as diarrhea, vomiting and intensive stomach pain.

The Mayo Clinic is a globally respected hospital and health and wellness conglomerate. Dr. James T. C. Li, M.D., Ph.D., is chair of the Division of Allergic Diseases in the Department of Internal Medicine and a board-certified asthma and allergy specialist. He also works as a consultant for the Mayo Clinic.

He points out that "People with allergy (or asthma) can lead full and healthy lives." Considering intolerance, since it is not near as serious as an allergy, Dr. Li says that simple dietary changes usually resolve the problem totally.

Here is what happens when you have a true allergic reaction to some type of food.

The symptoms you receive, mild or dangerous, come about because of the way your immune system reacts to a certain food. This could affect any number of organs. Your symptoms are not contained to your digestive system.

On the other hand, a food intolerance usually, but not always, limits its symptoms to your stomach area. In most cases this is not an immune system reaction. Your stomach, gut and gastrointestinal system simply have a hard time tolerating certain foods. In many cases, a food that causes a sensitivity or intolerance can be consumed in small quantities with no resulting symptoms.

What causes food intolerance?

You may lack special digestive enzymes that help break food down fully. Lactose intolerance is an example of this condition. Food poisoning, irritable bowel syndrome and sensitivity to food additives can also trigger a food intolerance.

If you continue to feel uncomfortable after eating a specific food, schedule an appointment with your doctor to determine if you are truly allergic, or simply intolerant to some type of food.