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Published on: 7/15/2026

What are the possible causes of an upset stomach?

Yoshinori Abe

Reviewed by Yoshinori Abe, MD

Internal Medicine

An upset stomach is most often caused by gas or bloating, which typically stems from benign issues such as poor digestion of certain foods, food intolerances, or reactions to additives and artificial sweeteners. Other common triggers include eating too quickly, overeating, stress, or mild indigestion. In most cases, symptoms resolve on their own without medical treatment.

However, an upset stomach can occasionally signal something more serious, such as an infection, ulcer, or chronic digestive condition. Because symptoms overlap across many possible causes, it's difficult to know for certain what's behind your discomfort without a proper evaluation. Taking a free, instant, online symptom check can help you better understand your symptoms, identify possible causes, and confidently decide on your next steps—all in just a few minutes.

Reviewed for medical accuracy: 07/14/2026

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Important Next Steps

Learn what may be causing upset stomachDiscover if your upset stomach needs careSee whether upset stomach is something seriousFind OTC relief for upset stomach symptomsFind doctors for stomach and digestive issuesUnderstand safe home remedies for upset stomachFind out what’s causing your stomach upset

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Explanation

There are a variety of causes of an upset stomach that run the gamut of common to very uncommon. Common causes of an upset stomach include poor digestion of certain foods (ie: dairy products, heavily processed foods, fried foods, etc. ), overeating, food poisoning or even stress. If persistent or intense, less common causes should be considered like an obstruction from a tumor, small intestinal bacterial overgrowth, gastric motility disorders or functional bowel issues like irritable bowel syndrome. To help identify what might be causing your symptoms, try our free AI-powered symptom checker for personalized guidance.

(References)

  • Hasler WL. Gas and Bloating. Gastroenterol Hepatol (N Y). 2006 Sep;2(9):654-662. PMID: 28316536; PMCID: PMC5350578.

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