At the moment, my nose is running like a faucet, my eyes are red and teary and my throat feels like it's on fire. Do I have an allergy? No, not this time, I've got a cold. The symptoms are rather similar but the cause is quite different.

We often use the term "allergy" as a shorthand because explaining "adverse reaction" requires more work, but "allergy" is a very specific technical term that implies a series of chemical reactions in your body. Just because you may be experiencing some of the symptoms that are in common with an allergic reaction doesn't mean you're having an allergic response.

Food allergies are very rare and often life threatening. Minute amounts of an allergen can trigger a response in the body, flooding the blood with chemicals called "histamines' in response to a misperceived invasion. (This is why we take "anti-histamines" to combat allergic responses) In the case of an allergy to pollens, the site of response is mainly in the nose, sinuses and eyes. In the case of a food allergy, the response is mainly in the mouth, throat, stomach and intestines. In cases of severe food allergy, anaphylactic shock may result, causing death if not treated immediately. Very few people have true food allergies and when they do the results are often violent and dramatic, leaving no room for doubt.

A more accurate term for the reaction that some people have to food additives would be "food intolerance". This would include feelings of lightheadedness from eating food containing MSG or Aspartame to the gassy feeling after consuming beans or dairy products (hence the term "lactose intolerant") Food intolerances may range from mild to severe - from simple feelings of discomfort to vomiting or diarrhea. While the response may not be pleasant, it's very rarely life threatening and shouldn't be confused with a true allergic response. Food Intolerance tends to be dosage related - you might be able to tolerate small amounts of cheese without a problem but eating a pizza can be the cause of distress. Even if you're food intolerant, you may be able to consume small amounts without any ill effect - this would not be the case if it were a true food allergy.

What kind of responses can you have from a food intolerance? Almost any. While an allergic response produces very specific symptoms (swelling, irritation, shock) a food intolerance may produce symptoms as diverse as sleepiness, dizziness, anxiety, restlessness, gas, diarrhea or other discomfort. In short, "intolerance" is can be used as a catch-all to describe any negative reaction, while "allergy" is a more specific medical term that describes an immune response to an antigen.

Webmaster's note: With that said, I often use the term "allergy" when describing my food intolerance to others. It's a convenient shorthand and is accurate enough for a simple social encounter. For situations that require a more accurate description (for example, publishing an informational website) I do my best to stay away from the term.