Reiki is universal life force energy. It is what we can't see, and we know it is there. We are all light, energy beings. Reiki practitioners are channels for the energy. We help people balance the energy in their body, by opening up the energy centers, or chakras.
When energy is stuck dis-ease can show up in the body, mind or spirit. By helping the energy flow, the body has a better chance of healing and restoring to balance. Reiki comes from the east and has been around long before western medical advancements. You can receive Reiki with all other treatments and medical interventions, without any harm.