Benicar and Benicar HCT Side Effects

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Drug Overview

Benicar is the brand name of a drug used to treat high blood pressure (antihypertensive) called olmesartan medoxomil. Benicar HCT is a combination drug containing olmesartan medoxomil with a thiazide diuretic, hydrochlorothiazide.

Olmesartan medoxomil is classified as a “prodrug” because the active form, olmesartan, is created in the body after the patient takes the medication. Olmesartan is classified as an angiotensin II receptor antagonist (AT1 subtype). This type of drug blocks a protein called angiotensin that causes blood pressure to rise by constricting blood vessels.

Hydrochlorothiazide, found in Benicar HCT but not Benicar, is a diuretic that increases urine production. It lowers blood pressure in two ways: in the short term, by decreasing blood volume and heart output (due to fluid loss through increased urination), and in the long term, by decreasing the resistance of peripheral blood vessels.

Benicar Side Effects

Benicar side effects are generally mild and relatively uncommon. Possible side effects include dizziness, upper respiratory tract infection (an illness similar to the common cold), abdominal pain, and diarrhea.

Benicar HCT Side Effects

Benicar HCT has all the same potential side effects as Benicar because they both contain olmesartan medoxomil. The hydrochlorothiazide in Benicar HCT can cause additional side effects, including electrolyte imbalances, other blood imbalances, headache, light sensitivity, nausea, and vomiting, all of which may be attributed to fluid loss due to the diuretic effect.

Benicar Warning During Pregnancy

Pregnant women should not take Benicar, Benicar HCT, or any other medication containing any form of olmesartan. The use of olmesartan in the second or third trimester is dangerous to the baby. It can cause death of the fetus or newborn or severe illness or injury in the newborn. Problems that have been reported in the baby include low blood pressure, underdevelopment of the skull, inability to urinate, kidney failure (sometimes irreversible), limb and facial deformation, and impaired lung development.

Olmesartan is in Pregnancy Category D, meaning that in rare cases, doctors may decide that the potential benefits outweigh the risks. A pregnant patient should be sure they understand all of these risks and benefits before taking Benicar or Benicar HCT, and her baby’s health should be carefully monitored throughout the pregnancy.


Benicar HCT Tablets (PDF) label from the FDA