Hyperbaric oxygen therapy (HBOT) utilizes 100% oxygen delivery at a pressure greater than 1 atm for the treatment of various emergent medical conditions including carbon monoxide poisoning. The most commonly associated complication of HBOT is middle ear barotrauma (MEB) which occurs when the eustachian tube does not allow air to enter the middle ear space to equalize the pressure between the ambient environment and the inner ear. Patients experiencing MEB usually feel pressure or pain in their ear(s). The spectrum of symptoms ranges from sensation of ear fullness and muffled hearing to severe pain, vertigo and tympanic membrane rupture. HBOT has not been studied. The investigators plan to perform a randomized double blind placebo control trial to determine if pseudoephedrine is effective in decreasing the rate of MEB during HBOT.