Most people are not born with allergies. In today's toxic environment the onslaught of chemicals in our immune system may weaken it and cause it to become faulty. It may then start reacting to perfectly normal foods and drinks as if they were a bacteria or a virus, which can result in rashes, headaches, diarrhea, vomiting or inflammation.

The branch of medicine which looks for allergies as a cause of illness is known as environmental medicine.