What Is Olmesartan? Uses, Dosage, and What You Need to Know in 2026

If your doctor just prescribed olmesartan, you probably have questions: What does it do? How do I take it? Is it safe? This plain-English guide covers everything a patient needs to know about olmesartan in 2026.

What Is Olmesartan?

Olmesartan medoxomil is a prescription medication used primarily to treat high blood pressure (hypertension). It belongs to a class of drugs called angiotensin II receptor blockers (ARBs). The brand name is Benicar; generic versions have been available since the mid-2010s. Olmesartan is also found in combination products:

Benicar HCT: Olmesartan + hydrochlorothiazide (a diuretic)

Azor: Olmesartan + amlodipine (a calcium channel blocker)

Tribenzor: Olmesartan + amlodipine + hydrochlorothiazide (triple combination)

What Is Olmesartan Used For?

Olmesartan received FDA approval in 2002 for the treatment of hypertension (high blood pressure) in adults. It was later approved for use in children 6 years of age and older. It can be used alone or with other blood pressure medications.

Lowering blood pressure with olmesartan helps reduce the risk of:

Stroke

Heart attack (myocardial infarction)

Kidney failure from long-term uncontrolled hypertension

Heart failure from hypertension-related cardiac damage

ARBs like olmesartan are also commonly used in patients with diabetes to help protect the kidneys from diabetic nephropathy, although this is an off-label use for olmesartan specifically (unlike losartan and irbesartan, which have specific FDA approvals for diabetic kidney disease).

Olmesartan Dosage: How Much Do You Take?

Olmesartan comes in three tablet strengths: 5 mg, 20 mg, and 40 mg. Here's how dosing typically works:

Adults: Starting dose is typically 20 mg once daily. After 2 weeks, the dose can be increased to 40 mg once daily if blood pressure isn't adequately controlled. Doses above 40 mg don't provide additional benefit.

Children (6-16 years): Dose is weight-based. Children weighing 20-35 kg: start at 10 mg/day (up to 20 mg/day); children >35 kg: start at 20 mg/day (up to 40 mg/day).

Volume-depleted patients: A lower starting dose may be used if you're dehydrated or taking diuretics.

How to Take Olmesartan

Take olmesartan once daily — at the same time each day.

Can be taken with or without food — food does not affect how well it's absorbed.

Swallow the tablet whole with a glass of water.

If you miss a dose, take it as soon as you remember — unless it's almost time for your next dose. Never double up.

If a child can't swallow a tablet, a pharmacist can make a liquid suspension — keep it refrigerated and use within 4 weeks.

How Long Does It Take to Work?

You may see some blood pressure reduction within the first week of taking olmesartan. The full effect is usually seen within 2 weeks. Peak plasma concentration is reached within 1-2 hours of taking a dose. At 20 mg/day, olmesartan typically lowers blood pressure by about 10/6 mmHg; at 40 mg/day, by about 12/7 mmHg compared to placebo in trials.

Is Olmesartan a Controlled Substance?

No. Olmesartan is not a controlled substance and has no DEA scheduling. It is a standard prescription medication. This means your doctor can prescribe it without special DEA oversight, you can fill it at any licensed pharmacy, and it can be prescribed via telehealth in most states.

To learn more about how olmesartan works in the body, read: How Does Olmesartan Work? Mechanism of Action Explained in Plain English

If you're having trouble finding olmesartan at your pharmacy, medfinder can help you locate a pharmacy with your dose in stock.