Yes, your body naturally tries to reject all foreign information, because it will try to maintain what it perceives as its natural state of being. So there is a small period of adjustment before your body accepts the new information, with some people this can be immediately with others this can be a few weeks. For example, a person with very low self confidence, wearing a Confidence item will naturally try to reject the effects of the field, because they have perceived themselves as ugly for so long, the new field of information conflicts with what their subconscious sees as right.
There is a way to make it quickly a part of you and to achieve greater effects, simply gold the item while meditating. At the gamma/epsilon brainwave state, where the majority of the brain is at that level (and it is very hard to have any form of awareness in this state) DNA accepts new information and integrates it in the chains. Of course the reflection of that change takes a while but it is entirely possible to add new information and or overwrite existing information.