How does Percy feel after he tries the strange drink Lightning Thief?

In "The Lightning Thief," Percy doesn't drink something called "strange drink Lightning Thief." Instead, he drinks something called "Diet Coke" that turns out to be actually the River Styx water, which temporarily makes him invincible. After drinking it, he feels extremely cold, as if his entire body is freezing, and he briefly loses consciousness because of the shock of the experience.