Nausea, Acid Reflux, and Scuba Diving

Have you ever experienced heartburn or felt nauseated during a dive? If you have, you are not alone. Recently, I received a question about nausea, heartburn and diving on scuba's Facebook page: "Is it normal to feel like throwing up after a dive? I've been diving for a year now, and I usually feel this acidity in my stomach after a dive or while diving. . . . When I dive, I usually go feet first in descending and maintain an almost horizontal position so that the acid in my stomach won't go to my throat."

The easiest explanation of nausea when scuba diving is seasickness. While many divers are familiar with seasickness on a boat, they may not be aware that it is possible to become seasick while in the water. Divers most commonly experience seasickness on the surface of the water or within the first fifteen feet below the surface, where the rocking wave motion can be felt. On dives with poor visibility, surge and wave motion from the surface can have an even greater effect on divers, as the lack of visibility obscures visual references points and makes orientation difficult.

"Pressure-triggered Gastroesophageal Reflux Disease occurs when a diver's body can not deal effectively with air expanding in the gastrointestinal tract."

Seasickness, however, is not the answer in this reader's case. He is an avid swimmer and snorkeler, and does not experience seasickness. The only situation in which he feels nauseated underwater is during a scuba dive, a fact which leads us to examine the differences between scuba diving and free diving (breath-hold diving).

One important way in which scuba diving differs from free diving is that a scuba diver's body can repeatedly absorb and release gasses while underwater as he breathes in and out. These gasses may effect a diver in various ways as the gasses expand and compress according to Boyle's Law.

After some internet research (keep in mind that I am not a diving doctor) I found a possible answer on

As a scuba diver descends, he must equalize his ears and other body air spaces. He does this consciously during the descent, and throughout the dive (sometimes unconsciously) as he makes small adjustments for minute changes in depth. Most divers swallow tiny amounts of air when they equalize, and therefore add small amounts of air to their stomachs throughout the dive. This is not generally a problem, but for some divers, the extra gas in the stomach can trigger the feeling of nausea as the gas expands and compresses with depth changes - even small ones. The greatest change in air volume is during ascent, so divers whose bodies are sensitive to gas in the stomach are likely to feel the worst during ascent and on the surface after a dive.

This condition has a name - Pressure Triggered Gastroesophageal Reflux Disease. It occurs in divers with a pre-disposition to the condition, whose bodies simply can not deal effectively with the air expanding in their gastrointestinal tract. The expanding air bubbles up through the esophagus along with stomach acid, causing the upper abdominal burning, chest pain, sour taste, and nausea associated with the condition. According to, this is not a dangerous problem unless it actually causes a diver to vomit underwater (which can lead to panic) or is experienced when the person has not been diving.

Suggestions as to how to deal with this issue include limiting the amount of food (and type of food) eaten before diving and the use of doctor-approved medicines to treat acid reflux. The scuba-doc website also suggests the use of over-the-counter antacid tablets, which may be the easiest solution to try first. Take a few antacid tablets before diving, or even carry them underwater if they come individually packaged (I had a client who used to do this!). Remember that a diving doctor's opinion should be sought before taking any medicine while diving. Normally innocuous medications may have strong or unusual effects while diving due to the increased pressure a diver experiences underwater.

Related links and articles

Read's Article on Acid Reflux and Diving
Read DAN's (Diver's Alert Network) Article On Stomach Problems and Scuba