What is Olmesartan: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Olmesartan medoxomil is a generic blood pressure drug. It belongs to a family of drugs called angiotensin receptor blockers (ARBs). It lowers blood pressure by blocking an enzyme that tightens and narrows blood vessels. Olmesartan medoxomil only comes as tablets, but a pharmacist can prepare a liquid version (oral suspension) from the tablets for easier dosing. One key warning is that olmesartan is never safe to take during pregnancy. Women should immediately inform the prescriber if they get pregnant.

Olmesartan overview

BRAND NAMES:

  • Benicar

Generic Names:

  • Olmesartan medoxomil

Uses:

  • Treats high blood pressure

Therapeutic Classes:

  • Antihypertensive, angiotensin receptor blocker (ARB)

Forms:

  • Tablet

How it’s taken:

  • By mouth

What is Olmesartan used for?

Olmesartan medoxomil treats high blood pressure in adults and children 6 years of age and older.

What form(s) does Olmesartan come in

  • Tablet 

    • 5 mg

    • 20 mg

    • 40 mg

What are common Olmesartan doses?

  • For high blood pressure:

    • In adults: 20–40 mg taken by mouth once daily 

    • In children weighing 35 kilograms (77 pounds) or more: 20–40 mg taken by mouth once daily

    • In children weighing between 20 kilograms (44 pounds) and 35 kilograms (77 pounds) or more: 10–20 mg taken by mouth once daily

Common Olmesartan prescriptions

  • Olmesartan Medoxomil
    30 tablets bottle

  • Olmesartan Medoxomil
    20mg tablet

  • Olmesartan Medoxomil
    40mg tablet

  • Olmesartan Medoxomil
    5mg tablet

How to take Olmesartan

  • Take this medicine as directed. The dose may change several times at the beginning of therapy.

  • Do not stop taking olmesartan medoxomil until talking to the prescriber.

  • Take doses without regard to meals.

  • Swallow the tablets whole with a drink of water.

  • If a pharmacist prepares an oral suspension, always shake the bottle before measuring a dose. Measure doses with a calibrated oral syringe or similar measuring device provided by the pharmacist.

  • Store the tablets at room temperature.

What to do if you miss a dose of Olmesartan

  • Ask the prescriber what to do in case a dose is missed. Instructions may vary between healthcare providers.

  • Do not take extra medicine to make up for a missed dose.

Olmesartan contraindications

  • This medicine is not right for everyone. 

  • Do not use it if you are pregnant.

  • Do not use it if you have had an allergic reaction to olmesartan.

Olmesartan warnings

  • It is not safe to take olmesartan during pregnancy because it could harm an unborn baby. Immediately inform the doctor if you become pregnant or think you’re pregnant.

  • Tell the doctor if you’re breastfeeding or planning to breastfeed. 

  • Before starting olmesartan, tell the prescriber if you have:

    • Kidney problems

    • Heart failure

    • Coronary artery disease

    • Recent strokes

    • Diabetes

    • High potassium

  • Olmesartan medoxomil can cause serious problems, including:

    • Low blood pressure

    • High potassium levels

    • Kidney problems

    • Elevated blood sugar

    • Severe allergic reactions

  • This medicine could lower your blood pressure too much, especially when you first use it or if you are dehydrated. Talk to the doctor if you feel dizzy or faint while taking this drug.

  • To avoid low blood pressure, drink plenty of fluids if you exercise, sweat more than usual, or have diarrhea or vomiting while you are using this medicine.

  • This medicine may cause severe chronic diarrhea with weight loss. This could occur months to years after you start taking this medicine.

  • Keep all appointments with healthcare providers. Regular doctor’s visits and blood tests can help prevent serious side effects.

Olmesartan interactions

  • To avoid possible drug interactions, tell the prescriber about all prescription drugs, over-the-counter medications, and supplements you take, especially:

    • The blood pressure drug aliskiren (contraindicated in people with diabetes)

    • Blood pressure drugs called ACE inhibitors

    • Drugs that make you pee (diuretics), particularly potassium-sparing diuretics

    • NSAIDs like aspirin or ibuprofen

    • The bipolar drug lithium

  • People taking the cholesterol drug colesevelam should take the day’s olmesartan dose at least four hours before or four hours after taking the colesevelam dose.

  • Ask your doctor before you use medicines, supplements, or salt substitutes that contain potassium.

  • Tell all other doctors that you’re taking olmesartan before they prescribe new medications.

Olmesartan side effects

Serious side effects

Talk to a doctor if you notice any signs or symptoms of a possible serious side effect, including:

  • Lightheadedness, dizziness, fainting

  • Change in how much or how often you urinate and bloody or cloudy urine

  • Severe diarrhea with weight loss

  • Rapid weight gain, swelling in your hands, ankles, or feet

  • Blistering, peeling, sores, red or purple skin rash

  • Allergic reaction: skin rash, hives, itching, facial swelling or puffiness, mouth swelling, swelling or tingling in the throat, chest tightness, difficulty breathing, 

Olmesartan medoxomil can cause serious side effects that may not have symptoms, including:

  • Injury or death of an unborn baby

  • High potassium

Less serious side effects

  • Headache

  • Dizziness

  • Upper respiratory tract infections

Sources:

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