One of the biggest reasons you feel better after an IV drip is because IV therapy rehydrates your body. The saline solution that acts as a base for the IV drip is incredibly efficient at rehydrating the cells in your body, offering you quick relief from the dehydration symptoms and giving your body a noticeable uptake in energy. Often symptoms you have experienced because of hydration (such as headaches or fatigue) will go away fairly quickly after the introduction of IV fluids into the body. In fact, many patients feel better almost immediately after getting IV treatment.