A woman in her 60s taking olmesartan for high blood pressure developed severe, watery diarrhea that landed her in the hospital. Doctors initially thought she had an infection, but when she got better and then got sick again after restarting the medication, they realized the blood pressure medicine itself was the problem. Tests showed her small intestine was damaged in a way that looked like celiac disease, but she didn’t have celiac. Once she stopped taking olmesartan, she improved without needing a special diet. This case teaches doctors to consider that medications can sometimes cause serious digestive problems that look like other diseases.
The Quick Take
- What they studied: Whether a blood pressure medication called olmesartan could cause severe intestinal damage and diarrhea that mimics celiac disease
- Who participated: One woman in her 60s who had high blood pressure, irregular heartbeat, and high cholesterol, and had been taking olmesartan for one year
- Key finding: The patient’s severe diarrhea, dehydration, and kidney problems were caused by olmesartan, not an infection or celiac disease. When she stopped the medication, her symptoms went away completely.
- What it means for you: If you take olmesartan and develop severe diarrhea, talk to your doctor immediately. This is a rare but serious side effect that doctors should consider. Do not assume it’s an infection or celiac disease without proper testing.
The Research Details
This is a case report, which means doctors documented the medical story of one patient in detail. The patient was a woman in her 60s who came to the hospital very sick with severe watery diarrhea, low blood pressure, dehydration, and kidney problems. Doctors initially thought she had an infection in her colon and treated her with supportive care like fluids and rest. She improved and went home, but when she restarted her regular medications (including olmesartan for blood pressure), her symptoms came back immediately. This pattern—getting better when stopping the medicine and getting worse when restarting it—was a major clue. Doctors then did a gastroscopy (a camera test to look inside the digestive system) and found severe damage to the small intestine that looked like celiac disease, but blood tests for celiac disease were negative.
Case reports are important because they alert doctors to rare side effects that might not show up in larger studies. This case is valuable because it shows a clear cause-and-effect relationship: the patient got sick when taking olmesartan, got better when stopping it, and got sick again when restarting it. This pattern strongly suggests olmesartan was the culprit. The case also teaches doctors not to assume that intestinal damage always means celiac disease or infection.
This is a single case report, which is the lowest level of scientific evidence. However, the evidence is strong because of the clear cause-and-effect pattern and the fact that stopping and restarting the medication produced predictable results. The diagnosis was confirmed with direct visualization of intestinal damage. The main limitation is that this happened in one person, so we cannot say how common this side effect is or who is most at risk.
What the Results Show
The patient experienced severe watery diarrhea for 20 days that caused dangerous dehydration, low blood pressure, and acute kidney injury requiring intensive care admission. Initial tests did not find any infectious cause like bacteria or viruses. After supportive treatment with fluids and rest, she improved and was discharged home. However, when she resumed her regular medications including olmesartan (which she had been taking for one year), the severe diarrhea and kidney problems returned within days, requiring readmission to the hospital.
A gastroscopy procedure revealed severe damage to the small intestine, specifically villous atrophy (flattening of the finger-like structures that normally absorb nutrients) and inflammation in the duodenum (the first part of the small intestine). This damage pattern looked very similar to celiac disease. However, blood tests specifically for celiac disease came back negative, ruling out that diagnosis.
The doctors concluded that olmesartan itself was causing a condition called olmesartan-related sprue-like enteropathy. This is a rare side effect where the blood pressure medication damages the intestines in a way that mimics celiac disease but is actually a drug reaction. Once olmesartan was discontinued, the patient’s symptoms improved significantly without needing any special diet or other treatment.
The case highlights the importance of recognizing that medications can cause serious intestinal damage. The patient’s kidney problems resolved once the medication was stopped, showing that the drug’s effects were reversible. The fact that symptoms returned so quickly after restarting olmesartan (within days) demonstrates a strong cause-and-effect relationship.
Olmesartan-related sprue-like enteropathy is a known but rare side effect that has been reported in medical literature. This case adds to the growing body of evidence that doctors should consider this possibility in patients taking olmesartan who develop severe diarrhea and intestinal damage. The case is particularly valuable because it shows the complete pattern: initial illness, recovery with medication discontinuation, and recurrence with medication restart.
This is a single case report involving one patient, so we cannot determine how common this side effect is or predict who is most at risk. We don’t know if other factors (age, genetics, other medications) made this patient more susceptible. The case does not include long-term follow-up information about whether the intestinal damage completely healed. We also cannot determine if this would happen to everyone taking olmesartan or only to certain individuals.
The Bottom Line
If you take olmesartan and develop severe or persistent diarrhea, contact your doctor immediately. Do not stop taking the medication on your own without medical guidance, but do report symptoms right away. Doctors should consider olmesartan as a possible cause when patients present with severe diarrhea and intestinal damage, especially if celiac disease and infections have been ruled out. This recommendation is based on a single case report, so the evidence level is moderate.
People taking olmesartan for high blood pressure should be aware of this rare side effect. Doctors treating patients with severe diarrhea and intestinal damage should consider olmesartan as a possible cause. This is particularly important for patients whose symptoms don’t fit typical patterns of infection or celiac disease. People with celiac disease or a family history of celiac disease should discuss olmesartan with their doctor.
In this case, symptoms developed after one year of taking olmesartan. Improvement began within days of stopping the medication, with significant clinical improvement occurring within the hospital stay. However, individual responses may vary, and this case cannot predict timing for other patients.
Want to Apply This Research?
- If taking olmesartan, track daily bowel movements (frequency and consistency) and any abdominal symptoms. Log any changes in energy level or signs of dehydration (dark urine, dizziness). Note the date and any medication changes.
- Set a reminder to report any new or worsening diarrhea to your doctor within 24 hours rather than waiting. Keep a simple log of digestive symptoms to share with your healthcare provider at appointments.
- Establish a baseline of normal digestive function when starting olmesartan. Monitor for any changes over the first few months and periodically thereafter. If diarrhea develops, track severity and duration to help your doctor assess whether it might be medication-related.
This case report describes a rare side effect of olmesartan in one patient and should not be interpreted as medical advice. If you take olmesartan, do not stop taking it without consulting your doctor. If you experience severe or persistent diarrhea, contact your healthcare provider immediately for proper evaluation. This information is for educational purposes and is not a substitute for professional medical diagnosis, treatment, or advice. Always consult with your doctor before making any changes to your medications.