Hi, First I would like to tell you about concussion. A concussion is basically a bruise that happens when the soft, jello-like brain bounces against the hard surface of the inner skull. The treatment is to rest the brain and let it heal. Air travel does present some unique conditions, and you’re right to ask about air pressure changes. At sea level, the air we breathe contains about 21 percent oxygen, while due to pressure differences on a typical commercial flight the cabin air has only about 15 percent oxygen. This can result in a slightly lower blood oxygen saturation for passengers while in the air. For healthy individuals , this small decrease usually goes unnoticed, however adults with recent head injury have reported an increase in symptoms like headache and nausea while on board. Consider pre-medication with a dose of acetaminophen or ibuprofen before boarding. It’s a good idea for him to be well-rested (or maybe sleep on the plane) and to stay hydrated during the flight. Encourage water rather than soda or fruit juices, as these can actually pull water out of the tissues. Since brain rest is recommended following a concussion, reading, watching movies and playing video games – things people normally do for entertainment on a plane – may make things worse. Instead, suggest your fiancee listen to quiet music or an audio book with the volume on the low side. Most mild concussions improve dramatically in two weeks, so he should wait for at least 2 weeks . Thanks.