An allergy is a condition in which your immune system regards an ordinary, harmless substance such as a food, pollen or dust, as a dangerous invader, and responds to it by producing its own antibodies to attack the substance.
This is when you suffer from one or more unpleasant symptoms. An allergy normally causes an instant reaction, such as in the case of a peanut allergy. However, with an intolerance, the culprit, such as milk or wheat, is usually eaten every day.
Therefore your symptoms, caused by the intolerance, never improve, and it is difficult to find the underlying cause.Medication may help to treat the symptoms, but not the root cause. If your symptoms don't clear up after a reasonable amount of time, then the root cause could be an intolerance