Relief beneath the waves

Pseudoephedrine is unlikely to cause changes in cognitive or cardiac function at a depth of 66 feet below water surface, but dimenhydrinate "adversely affects mental flexibility" and may contribute to the dangers of scuba diving, University of Pittsburgh researchers report in the September issue of Pharmacotherapy. Divers often take the drugs before submerging to reduce sinus congestion and motion sickness, but dangerous side effects may exist. "Although the magnitude and clinical significance of...risk are difficult to quantify, routine and widespread use of dimenhydrinate before scuba diving is not recommended," David Taylor, MD, et al. write. The double-blind, placebo-controlled, crossover studies examined the psychometric and cardiac effects of the drugs on 30 active divers using a hyperbaric chamber