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Benicar Side Effects

Benicar (olmesartan medoxomil) is a prescription drug that can cause serious, sometimes deadly, side effects and complications. The most notable adverse reactions include fetal toxicity, resulting in injuries and/or death to fetuses if taken during pregnancy, and sprue-like enteropathy, resulting in severe gastrointestinal symptoms most commonly associated with celiac disease.

Benicar, a popular high blood-pressure medicine, has been linked to several very serious side effects, including one with severe gastrointestinal symptoms.

The complication triggers diarrhea so severe that it can cause substantial weight loss and malnutrition, as well as permanent damage to the small intestine. More than 2,000 people who developed these side effects filed Benicar lawsuits.

Benicar’s label also has a black box warning for fetal toxicity. The drug is not recommended during pregnancy because of potentially serious and often fatal conditions in fetuses. Even if the fetus survives to birth, the medication’s adverse effects can cause severe health complications for infants that can persist into adulthood.

Benicar is also linked to some less severe but still serious conditions requiring continued monitoring, including:
  • Low blood pressure in patients with dehydration and low sodium levels
  • Impaired kidney functioning, rarely leading to kidney failure and/or death
  • Electrolyte imbalances, including elevated levels of potassium in the blood serum

Research has linked olmesartan, the active ingredient in Benicar, to fetal toxicity, especially when taken during the second and third trimesters of pregnancy. The drug’s label contains a black box warning that states that drugs, such as Benicar, that act directly on the renin-angiotensin system “can cause injury and death to the developing fetus.”

Potential Threats Include:
  • Fetal kidney failure
  • Low amniotic fluid, resulting in fetal lung underdevelopment or failure and skeletal deformations
  • Skull underdevelopment
  • Retention of urine
  • Low blood pressure
  • Kidney failure after birth
  • Death

Benicar can also cause disease for children 1 and under. The drug has been found to have certain effects on the development of immature kidneys.

Benicar and Fetal Kidney Failure & Urinary Tract Complications

A fetus’ kidneys start to grow during the first month of pregnancy. An ultrasound can allow a doctor to see the baby’s internal organs, including the kidneys, prior to birth, usually starting in the second trimester. This test can also detect abnormalities in the developing kidneys and urinary tract. In general, one in about 500 births has some abnormality occur in the development of the kidneys or urinary tract, according to the National Kidney Foundation.

Kidney dysplasia

Problems with kidneys can lead to complications after birth. Kidneys are essential to urine production and the maintenance of electrolyte levels and fluids in the body. Kidney dysplasia, also referred to as multicystic dysplastic kidney, is a condition in which the internal structures of one or both of the fetus’ kidneys do not develop normally.

In this fetal condition, the kidneys have tubules (these tiny structures collect urine while the fetus is in the womb) that fail to completely branch out. The urine that would normally go into the tubules has nowhere to go and instead collects inside the affected kidney. This results in the formation of fluid-filled sacs called cysts, which replace normal kidney tissue preventing the kidney from functioning properly.

Dialysis, Transplant

Kidney dysplasia, or underdevelopment, can affect one or both kidneys. When the condition is severe, babies typically will not survive birth. Those who do survive require immediate treatment, including dialysis (to filter the blood) and a kidney transplant. Treatment is postponed or not needed in babies with mild dysplasia, or in those with dysplasia affecting only one kidney.

There is no cure for multicystic dysplastic kidney, but it is a fairly common occurrence, with scientists estimating that it affects about one in 4,000 babies. About half of babies diagnosed with the condition are also diagnosed with other urinary tract defects. One such defect is anuria, which occurs when the kidneys stop producing urine.

Urine production

Urination is important to remove wastes and excess fluids from the body. The kidneys produce about one to two quarts of urine each day, and filter about 120 to 150 quarts of blood. Children produce less urine than adults. When a person does not urinate, wastes, fluids and electrolytes can build up in the body, complicating health problems and possibly resulting in death.

Certain factors increase a baby’s chances of developing kidney dysplasia, including:
  • Parents who have genetic traits for the condition
  • Certain genetic syndromes affecting multiple body systems
  • Pregnant mothers who use certain prescription medications, such as Benicar, or illegal drugs

Symptoms and Complications of Kidney Dysplasia

Some babies may not show any signs or symptoms of kidney dysplasia if only one kidney is affected. Sometimes the affected kidney may be enlarged at birth or cause the infant pain. Complications associated with kidney dysplasia can lead to permanent damage to one or both kidneys, which can progress to chronic kidney disease and possibly lead to kidney failure and/or death.

Kidney dysplasia complications can include:
(literally meaning “water inside the kidney”) of the working kidney when only one kidney is affected – a condition where one or both kidneys become stretched and swollen due to the build-up of urine inside of them; if left untreated, this condition can lead to kidney damage.
Urinary tract infection (UTI):
urinary blockage can increase a baby’s chance of developing a UTI; these infections can be recurring leading to kidney damage
High blood pressure
Slight increase in the risk of developing kidney cancer

Treatment of Kidney Dysplasia

When kidney dysplasia is limited to one kidney and the baby is not experiencing any symptoms, treatment is likely not necessary. When the condition is more severe, or affecting both kidneys, patients may eventually need dialysis or surgery, including a kidney transplant. Regular check-ups will be needed regardless of an infant’s overall health.

Doctor checking girl's blood pressure
These routine appointments will include:
  • Blood pressure checks
  • Blood testing to measure kidney function
  • Urine testing for albumin
  • Ultrasounds to monitor kidney damage

When only affecting one kidney, babies with kidney dysplasia have a good long-term outlook. The affected kidney may shrink as the child grows, becoming unable to be seen on X-ray or ultrasound by about age 10. This results in the child living with a solitary kidney, or just one working kidney, with few, if any, health complications. If urinary tract problems are present, kidney failure of the solitary kidney may result, requiring dialysis or a transplant operation.

When both kidneys are affected, children are more likely to develop chronic kidney disease. Patients will need to be seen by a pediatric nephrologist, who is a doctor that specializes in the care of children with kidney disease. Dialysis and a kidney transplant may eventually be needed.

Some tips for keeping kids with kidney dysplasia healthier longer, according to KidsHealth from Nemours, include:
  • Limiting their sodium, dairy and protein intake (such as meat, fish or eggs) to lessen the work of filtering required by the kidneys and potentially delaying the need for dialysis
  • Limiting and monitoring fluid intake
  • Refraining from contact sports to protect the kidneys from injury
  • Getting regular exercise and maintaining an ideal body weight
  • Having blood pressure routinely checked

Benicar's Severe Gastrointestinal Side Effects

In 2013, the FDA issued a safety announcement that the blood pressure drug Benicar (olmesartan medoxomil), as well as similar drugs such as Benicar HCT, Azor, Tribenzor and generic versions, can cause severe intestinal complications with side effects collectively known as sprue-like enteropathy. Patients experiencing olmesartan-induced sprue-like enteropathy exhibit signs and symptoms similar to individuals suffering from celiac disease.

Signs and symptoms of sprue-like enteropathy
Signs and symptoms of sprue-like enteropathy
  1. Severe, chronic diarrhea
  2. Substantial weight loss
  3. Malabsorption
  4. Abdominal pain
  5. Fatigue
  6. Bloating
  7. Nausea
  8. Vomiting
  9. Anemia

This condition can develop months or even years after the patient first starts taking Benicar or other medications containing olmesartan. In severe cases, patients can end up hospitalized and/or suffer from permanent intestinal damage, or villous atrophy (the destruction of intestinal villa that helps with the absorption of nutrients from food). The condition usually resolves once the offending drug is discontinued.

Villous Atrophy (Permanent Intestinal Damage)

Most often, when patients take prescription medications that cause diarrhea, such as Benicar, the side effect occurs without permanent damage to the intestines. But when villous involvement and malabsorption are present, the resulting damage to the intestines is called sprue-like enteropathy. This condition is typically associated with celiac disease due to gluten exposure. However, drug-induced enteropathy can occur independent of gluten intake.

Sprue-like enteropathy Warning
Sprue-like enteropathy can develop months or even years after taking Benicar or another medications containing olmesartan.

Villous atrophy occurs when the intestinal villi (microscopic, finger-like projections) erode away, causing the walls of the small intestine to essentially become a flat surface. The villi help absorb nutrients from the foods we eat. If they are destroyed, resulting in villous atrophy, patients can experience serious nutritional deficiencies.

Villous Atrophy Detection

The only way to detect and diagnose villous atrophy is to look directly at the walls inside the small intestine. This can be done through a procedure called an endoscopy, which uses a camera on the tip of a small medical instrument. The instrument is threaded down the throat, through the stomach and into the small intestine.

Drug-induced diarrhea can occur for any number of reasons. Its cause is uncertain in patients taking Benicar. Due to its lag time in patients taking the high blood-pressure medication, developing months to years after the start of treatment, most researchers believe it is a hypersensitivity (allergic) response.

Please seek the advice of a medical professional before making health care decisions.

Related Pages

Kristin Compton's background is in legal studies. She worked as a paralegal before joining Drugwatch as a writer and researcher. She was also a member of the National Association of Legal Assistants. A mother and longtime patient, she has firsthand experience of the harmful effects prescription drugs can have on women and their children. Some of her qualifications include:

  • Bachelor of Arts in Legal Studies | Pre-Law from University of West Florida
  • Past employment with The Health Law Firm and Kerrigan, Estess, Rankin, McLeod & Thompson LLC
  • Personal experience battling severe food allergies, asthma and high-risk pregnancies
Edited By

10 Cited Research Articles

  1. Anderson, J. (2016, November 9). What Is Villous Atrophy and What Conditions Cause It? Retrieved from:
  2. Cherney, K. (2017, June 12). Anuria. Retrieved from:
  3. National Institutes of Health. (2017, April 25). Label: Olmesartan Medoxomil – olmesartan medoxomil tablet. Retrieved from:
  4. Dowshen, S. (2014, February). When Your Child Has a Chronic Kidney Disease. Retrieved from:
  5. U.S. Food and Drug Administration. (2013, July 3). FDA Drug Safety Communication: FDA approves label changes to include intestinal problems (sprue-like enteropathy) linked to blood pressure medicine olmesartan medoxomil. Retrieved from:
  6. National Kidney Foundation. (2015). Detecting Kidney and Urinary Tract Abnormalities Before Birth. Retrieved from:
  7. The National Institute of Diabetes and Digestive and Kidney Diseases
  8. Health Information Center. (2015, July). Kidney Dysplasia. Retrieved from:
  9. U.S. National Library of Medicine. (2017, October 2). Drug Record: Olmesartan. Retrieved from:
  10. Tran, T. and Li, H. (2014, January). Olmesartan and Drug-Induced Enteropathy. Retrieved from:
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