Volume , Issue

In 1981, Drs. Paul Auerbach and York Miller first reported the phenomenon of High Altitude Flatus Expulsion (HAFE) in the medical literature. There was a flurry of letters in response to this discovery proposing pathologic mechanisms and potential impacts. However, little was done by the medical establishment to prove the syndrome’s mechanism or discover a solution to prevent psychological trauma to those afflicted. Some cures have been proposed in the lay press, but no reports on the efficacy of these treatments exist.

In April of 2022, along with 15 other fourth-year medical students, I ascended more than 10,000 feet above sea level to Breckenridge, CO, to participate in a Wilderness Medicine elective. The report from Drs. Auerbach and Miller prepared us for an increased frequency and volume of Rocky Mountain Barking Spider attacks, but we did not know what to expect of the pungence of our flatus. We hypothesized odor would be significantly reduced because of a dilutional effect since the proposed mechanism of HAFE is the expansion of colonic gas due to decreased atmospheric pressure following Boyle’s Law. Yet, we were surprised when we discussed our wind-breaking habits on arrival at altitude.

First, about half of our group did not notice any change in our flatus frequency, volume, or odor. Of course, we were below the threshold of 11,000 feet proposed by Auerbach and Miller, but many of us came from sea level and, by Boyle’s Law, would expect a 44% increase in the volume of flatus. Those who noticed an increase in volume and frequency of flatus reported a return to normal gaseous levels after about two days, which is also noted in the lay literature. These observations fly in the face of the proposed mechanism of HAFE.


If there is a threshold altitude to experience HAFE and the syndrome resolves after two days, the actual mechanism may have more to do with the physiologic adaptation of the gut microbiome than gas laws. Given the focus on the gut microbiome in the GI literature, it could be vital to uncover this mechanism. Of course, many confounders such as dietary changes and response bias limit our anecdotal observations. We must fortify the scientific literature surrounding HAFE. We would like to recommend conducting two different studies to explore HAFE. To find the best prevention method for those suffering from HAFE, we recommend the Full Avoidance of HAFE in Recreational Travelers (FAHRT) Trial. To better understand the mechanism of HAFE, we find it vital to conduct the Scientifically Computing HAFE Intensity in Travelers (SCHIT) Study.

Photo Credit: Lydia North

We believe further inquiry into HAFE is essential for our understanding and will propel discovery forward. With additional knowledge, we may uncover the secrets to an earlier return of normal bowel function in postoperative patients. We may be able to push the limits of how many people can sleep in a single room with inadequate ventilation. Like many medical discoveries, we may find more that we can do for our patients by understanding physiologic adaptations in extreme environments. It is fitting that Wilderness Medicine lead this charge.

Additional References:

1. Auerbach P, Miller YE. High Altitude Flatus Expulsion (HAFE). West J Med. 1981;134(2):173-174.
2. Davis EY. HAFE in Nepal. West J Med. 1981;134(4):366.
3. Anderson OW. Horse HAFE?. West J Med. 1981;135(3):242.
4. Geehr E. More HAFE. West J Med. 1981;134(5):449.
5. McElroy CR, Hoffman JR. Still More HAFE. West J Med. 1981;134(6):546.
6. https://www.livestrong.com/article/13767342-hafe-high-altitude-gas/

You Might Also Be Interested in

A Maltese Medic’s Mission in Madagascar

MD, MRCPCH, MSc, MAcadMEd5/27/2024

Physician perspectives, part 2

A Maltese Medic’s Mission in Madagascar

Jamie A. Grech, MD, MRCPCH, MSc, MAcadMEd4/18/2024

Physician Perspectives: Part 1

Doctoring Aboard an Arctic Expedition Ship

M. J. Hessert, DO, MPH, FAWM8/15/2022

Managing COVID and other illnesses at sea

High Altitude Flatus Expulsion

David Wilson, MDLara Phillips, MD7/11/2022

A pungent phenomenon examined