Star Trek: Enterprise: Season 3, Episode 16 - ProjectFreeTV

3 - 16: Doctor's Orders

Archer places Dr. Phlox in control of the Enterprise when the crew requires sedation to survive a trans-dimensional disturbance. This mind-altering section of the Expanse is lethal to humanoids. But Phlox's Denobulan physiology doesn't entirely shield him from its effects, causing hallucinations.