Your digestion was predictable before COVID. Now you’re constipated for days, bloated by afternoon, or swinging between extremes. Your stomach feels full after a few bites. Maybe you’ve been told it’s stress, or that it’s just IBS.
Gut symptoms are among the more common and less discussed parts of long COVID. They deserve a real look.
What the research shows
A large U.S. Department of Veterans Affairs cohort study (Xu, Xie, and Al-Aly, Nature Communications, 2023) followed people for a year after COVID infection. Compared with people who had not been infected, they had a higher risk of several gastrointestinal disorders, including:
- functional bowel conditions such as irritable bowel syndrome,
- acid reflux, and
- other digestive problems.
The RECOVER study, the largest U.S. long COVID research effort, also lists GI symptoms among the complaints reported after infection.
Common gut symptoms after COVID
- Constipation, or constipation alternating with loose stools
- Bloating and abdominal distension, often worse as the day goes on
- Feeling full quickly, or nausea after meals
- Reflux or upper abdominal discomfort
- New sensitivity to foods that used to be fine
- Abdominal pain without a clear cause on standard testing
Why COVID can affect the gut
Researchers have proposed several connections:
- The nervous system runs digestion. Gut motility is controlled largely by the autonomic nervous system. When that system is disrupted, as it is in POTS and other forms of dysautonomia, digestion often slows. That’s one reason constipation and bloating so often travel with dizziness and a racing heart after COVID.
- The microbiome may shift. Studies have reported changes in gut bacteria after COVID infection. What that means for individual symptoms is still being studied.
- Immune and mast cell activity may contribute to reactions to foods that were previously well tolerated.
What about SIBO?
Small intestinal bacterial overgrowth (SIBO) comes up often in long COVID discussions. A link is plausible, because slowed gut motility is a known risk factor for SIBO. But research specifically connecting SIBO to long COVID is limited.
Breath testing for SIBO also has real limitations and can produce both false positives and false negatives. Results should be interpreted alongside your symptoms rather than on their own.
Why standard workups often come back normal
A colonoscopy, an abdominal CT, and routine bloodwork can all be normal in people with significant post-COVID gut symptoms. Those tests look for structural disease: tumors, inflammation, and blockages. They’re important for ruling out serious problems, but they aren’t designed to measure how well the gut is moving or how the nervous system is regulating it.
How it is evaluated
A thorough evaluation considers:
- Timeline: when the gut symptoms started relative to COVID, and what else changed at the same time.
- The full symptom picture: whether dizziness, rapid heart rate, fatigue, or brain fog came along with them.
- Prior testing: what has already been ruled out.
- Targeted testing where appropriate: our lab testing page explains the testing we use and what each test measures.
- Coordination: with your gastroenterologist or primary care clinician when further workup is needed.
Warning signs that need prompt evaluation
See a physician promptly, or go to the emergency room if symptoms are severe, for:
- blood in the stool or black, tarry stools,
- unintentional weight loss,
- vomiting that won’t stop,
- severe or worsening abdominal pain,
- difficulty swallowing, or
- a new change in bowel habits after age 45.
Structural causes need to be ruled out first.
Serving Oklahoma City, Tulsa, and all of Oklahoma
Venturis Clinic sees patients from Oklahoma City and surrounding areas, including Tulsa, as well as from across Oklahoma. Gut symptoms after COVID are often part of a larger pattern. Our Long COVID Treatment in Oklahoma City page explains how we look at that pattern as a whole.
Frequently asked questions
Can COVID cause constipation months later? Large studies have found higher rates of digestive disorders in the year after infection, and many people report constipation as part of long COVID. Other causes should still be ruled out.
Is this just IBS? Some people meet IBS criteria after COVID. The label describes the symptom pattern, but it doesn’t explain what is driving it. That’s worth investigating, especially when other long COVID symptoms are present.
Should I get tested for SIBO? It can be reasonable in the right context. Breath test results should be interpreted carefully alongside your symptoms and history.
Why do my gut symptoms get worse when I’m upright or tired? Digestion depends on the same nervous system that regulates heart rate and blood pressure. When that system is under strain, gut function often suffers too.
Ready to get to the bottom of it? Book a free 15-minute discovery call, or learn more about long COVID care in Oklahoma City.
This page is for educational purposes and is not a substitute for individual evaluation.
By Alvin Philipose, DC, ICCP
Sources
- Xu E, Xie Y, Al-Aly Z. Long-term gastrointestinal outcomes of COVID-19. Nature Communications. 2023;14:983.
- Thaweethai T, et al. Development of a definition of postacute sequelae of SARS-CoV-2 infection. JAMA. 2023;329(22):1934–1946.