Gas-X Side Effects

Gas-X is the brand name for an over-the-counter medication used to treat excessive gas in the stomach. Even though this medication is effective, safe and used by many people, additional information will enable better understanding of how it works and any potential side effects.

Symptoms and Causes

The symptoms of too much gastrointestinal gas are quite well known—bloating, pressure, feeling too full, and subsequent abdominal pain, flatulence and belching. There are several reasons why excess gas becomes trapped, but the most common causes are certain foods, such as beans and cabbage, eating too quickly, swallowing air and carbonated drinks. Certain medical conditions can also lead to trapped gas. The most common are chronic indigestion, ulcers, irritable bowel syndrome and diverticulosis.

How Gas-X Works

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The active ingredient in Gas-X is simethicone. It is considered to be an “anti-foaming” agent that works by decreasing the surface tension of the many gas bubbles causing the uncomfortable symptoms. Simethicone does not reduce the amount—or prevent the formation—of gas. It works by increasing the speed with which the gas leaves the body.

Surface Tension

What does decreasing surface tension have to do with expelling gas more quickly? Surface tension refers to the fact that molecules attract one another—pulling each one toward the other—and this creates tension. This tension is stronger in the center where there are more molecules pulling toward one another from all sides. Toward the surface, this “pull” results in shrinking the surface area and that creates the surface tension. When simethicone reduces the surface tension of gas bubbles, it is easier for them to be expelled.

Side Effects

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Simethicone works in the stomach to disperse trapped gas. It is not absorbed into the blood so it is considered to be very safe. No significant side effects have been reported, but it is possible that Gas-X may cause mild diarrhea and heartburn. On the very rare chance that you are allergic to this medication, be sure to immediately seek professional help. The typical symptoms of a serious allergic reaction are rash, itching, swelling, dizziness and breathing.


The dosage directions on the package should always be strictly followed. Do not take other simethicone containing medications at the same time as Gas-X without first talking to your physician. If you are pregnant, have liver or kidney disease, or any other illness it is also advisable to consult a physician before taking even such a safe medication to be sure it won’t interact with other medications you may be taking.