Houston Methodist Teams Up with NASA to Probe Spaceflight's Impact on Sinonasal Health

As humanity pushes the boundaries of space exploration, researchers at Houston Methodist Hospital are helping answer a surprisingly down-to-earth question: What happens to your sinuses in space?

The study examined nearly two decades of medical records from astronauts aboard the International Space Station (ISS) and found that sinonasal symptoms — especially nasal congestion — are among the most common health issues encountered in orbit.

"Astronauts are typically among the fittest individuals on the planet, yet this study shows that even they experience substantial sinonasal complaints in space," said Dr. Mas Takashima, chair of the Department of Otolaryngology – Head and Neck Surgery at Houston Methodist and the study's primary investigator. "Imagine what happens when civilians with preexisting conditions start traveling to space."

The study, published in Laryngoscope Investigative Otolaryngology, analyzed 754 medical events from 71 astronauts from 2000 to 2019. The striking findings: 85% of astronauts experienced at least one sinonasal issue, with nasal congestion affecting three out of every four.

Frequent research collaborations with NASA places Houston Methodist at the forefront of aerospace medicine as interest in long-duration space missions and civilian spaceflight grows. The team's retrospective study leveraged NASA's Lifetime Surveillance of Astronaut Health (LSAH) database to identify patterns in sinonasal complaints and medication usage.

Microgravity and pressure changes

The root cause of extraterrestrial sinonasal issues appears to lie in the body's reaction to microgravity. Without gravity pulling fluids downward, astronauts experience a cranial fluid shift where blood and other fluids move toward the head, causing facial puffiness and nasal congestion.

"Most symptoms occurred during the first week of spaceflight, supporting the fluid shift hypothesis," said Dr. Takashima. "But we also saw a steady stream of issues persisting beyond six months of spaceflight, suggesting other factors may also be at play."

Pressure changes during extravehicular activity (EVA), or spacewalks, likely compound the issue, Dr. Takashima says. Astronauts transitioning from the ISS cabin pressure of 14.7 psi to suit pressures as low as 4.3 psi can experience tissue expansion in the sinuses and middle ear, leading to congestion, barotrauma and Eustachian tube dysfunction.

The study found astronauts who participated in EVA had significantly more sinonasal medical events — on average, nine more — than those who didn't.

Medication use and limitations

To manage symptoms, astronauts often turn to over-the-counter decongestants. Pseudoephedrine and oxymetazoline (Afrin) were the most commonly used medications, often self-administered before EVA. But their long-term efficacy in space is uncertain.

"These medications may not work the same in microgravity," said Dr. Takashima. "And frequent use of Afrin, for example, can lead to rebound congestion, a serious issue if you're relying on it every time you suit up for EVA."

Other medications, including antihistamines, were also used to treat presumed allergic reactions, possibly triggered by airborne particles that linger longer in microgravity. HEPA filters help mitigate this, but astronauts remain vulnerable to nasal irritation from daily activities such as shaving or eating.

Implications for spaceflight

With NASA's Artemis missions and eventual crewed flights to Mars on the horizon, long-duration spaceflight will only increase. The study suggests that preemptive measures such as screening for sinus conditions and minor otolaryngological procedures like turbinate reduction may be warranted for future astronauts.

"In cases where astronauts already suffer from nasal obstruction, a minimally invasive turbinate reduction might help reduce the risk of congestion in space," said Dr. Takashima. "It's something we're beginning to consider more seriously."

Beyond symptom management, researchers also emphasize the need for further prospective studies to identify optimal treatments and preventive strategies tailored to the unique environment of space.

"This is about maintaining peak performance," Dr. Takashima said. "If you're not sleeping well because you can't breathe, your cognitive function, reaction time and mission performance can suffer, and those things are absolutely critical in space."

Interestingly, the project featured an unusual reunion. Dr. Takashima attended medical school with Dr. David Hilmers, an astronaut who flew on the space shuttle before choosing to become a physician. Dr. Hilmers, now with the Center for Space Medicine at Baylor College of Medicine, collaborated on the study and is a co-author of the publication.

"Dave has a unique perspective that bridges astronaut experience and medical insight," said Dr. Takashima. "His input was invaluable in understanding the practical realities of life in space."