Allergies are immune overreactions to particular triggers. The body treats the food as a foreign object and tries to get rid of it.
An intolerance is when the body doesn't produce enough of an enzyme (if you're lactose intolerant, your body doesn't produce enough lactase, for example). The symptoms of an intolerance are annoying and can be temporarily disabling but aren't fatal. An allergy can be fatal, so it's extremely important to know the difference.
Most people are familiar with allergies- rashes and hives breaking out around the face, mouth or even swelling around the face/tongue or lips, flushed skin or coughing or wheezing. Diaper rash can be a sign of an allergic reaction instead of a normal diaper rash.
[caption id="" align="alignnone" width="720"] Via MomJunction[/caption]
Food intolerance is something people don't pay as much attention to but the major symptoms are bloating, excessive gas, vomiting, nausea, diarrhea or even constipation.
Diarrhea and vomiting can be signs of either an allergy or intolerance. Since one is serious and the other isn't as serious, how can you tell the difference? The first thing you need to do is keep a log of what baby has been eating, call your doctor and set up an appointment to get a referral for allergy testing.
There are three types of allergy testing- blood, skin prick/injection, and food elimination diets. Since the baby is tiny, there likely will only be a blood test run or an elimination diet.
Blood tests test for the presence of certain antibodies. They will simply need to draw one vial to do the testing. They aren't always as sensitive as skin prick testing, so they can miss allergies.
In skin prick testing, they take the allergen and prick your skin. It feels like being scratched- if a hive develops, it usually means you're allergic but if no reaction, it means you're clear. Skin injections can be done if the prick test comes back all negative. They take the allergen and inject it under your skin- it works like the skin prick test.
The elimination diet works by eliminating all potential allergens from your diet for a period of time (normally a month), keeping a log of everything you feed the baby then adding each item back one at a time and watching for symptoms. The elimination diet is harder to keep up with and cross contamination or accidental mixing of allergens can possibly cloud the results, though.
There are some symptoms that are almost only seen in allergies, some that are almost only seen in intolerance, but there are many overlapping symptoms and if not treated properly, an intolerance can escalate into an allergy. It's always important to see a doctor when it comes to potential allergies, but while you're waiting to get baby in to see the doctor- you can start food logging and taking notes to give the pediatrician.