When our immune system is over burdened with toxins it becomes suppressed. Different people are allergic to different things but the most common are molds, dusts, animal dander, and pollens. However, if the body is already overwhelmed by trying to detoxify itself, a person can become allergic to almost anything. I have no idea which oils have contributed to this wonderful change. I think they all must be playing a part.
Oils help the body in many ways.
When applied to the skin or inhaled, essential oils have the ability to dramatically increase cellular oxygen. This begins, almost immediately to boost the immune system. One of the Young Living workshops I attended Dr. Essman did a visual illustration that helps to understand why the oils are helping with allergies. He talked about how the oils digest the petrochemicals in the body. To illustrate, he used the overhead projector.