Hello, Taking flight for pleurisy patients is discouraged as respiratory distress and pulmonary embolism are two complications that may occur. Pleurisy patients who are quite ill should not take flight and should focus on getting treated first. Sometimes, patients suffering from pulmonary diseases may suffer from fatal consequences due to lower oxygen levels in the cabin. Due to changes in the atmospheric pressure they may develop breathing problems, hypoxia, chest discomfort, light headedness, racing heart beat, skin tingling or numbness. Risk is high if it is due to a blood clot, if the blood clot ruptures it may enter the brain(brain stroke) or the heart (heart attack). Your Bf should consult the treating doctor, he can only take a flight if fit-to -fly assessment is given. He may not be given fitness to take the flight if mid flight medical emergency is high. Get him treated at the earliest. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician