We thank Mr. Pun and Dr. Ghimire and Dr. Basnyat for their interest and comments on our recent publication. When we designed and performed our study, Richalet and colleagues (1) and Aldashev and colleagues (2) had not yet published their work on sildenafil, which both showed that sildenafil decreases hypoxic pulmonary hypertension. Sildenafil must be taken in rather brief intervals because of its short half-life of 4 to 5 hours. Because we tested the effectiveness of 2 drugs in our study, we needed to match the time of drug intake and chose the phosphodiesterase-5 inhibitor tadalafil with a long half-life (17 hours). The recommended dose of tadalafil to treat erectile dysfunction is 10 to 20 mg; thus 10 mg of tadalafil every 12 hours seemed reasonable.

Rock and colleagues (3) reported that 4 mg of dexamethasone every 12 hours statistically significantly reduced symptoms and signs of acute mountain sickness, whereas 1 mg or 0.25 mg of dexamethasone was ineffective. We decided to increase the dose to the maximum used to treat acute mountain sickness, which was 16 mg/d (8 mg twice daily) on the basis of previous trials that used 4 mg four times daily. On the basis of our participants' clinical background, applying this dosage on only 4 consecutive days seemed safe, an assumption that was confirmed in our study.

Dr. Basnyat noticed that we did not comment on possible dangerous mental side effect of dexamethasone. During our study, we assessed the mental status of all participants daily and did not observe any symptoms of inappropriate euphoria or mental disorientation. Moreover, to our knowledge, no studies indicate that dexamethasone impairs cognitive functions at high altitude. Conversely, 2 studies on mountaineers at altitudes higher than 4000 meters, who received 8 to 16 mg of dexamethasone daily, showed an improvement of reaction times and mood status but no effects on personality in cognitive and psychomotor tests (4, 5). Thus, these results suggest that the use of dexamethasone at high altitude might even improve a mountaineer's awareness while climbing exposed ridges or trekking paths. However, we cannot generally recommend the routine use of dexamethasone for high-altitude pulmonary edema prophylaxis for longer than a few days because of its well-known long-term side effects and the lack of safety data in the context of a trekking or climbing expedition in remote areas.