How does Olmesartan Work?

How does Olmesartan work?

How Does Olmesartan Work?

Olmesartan works by stopping the angiotensin II hormone from activating a receptor in the body that usually leads to a slight increase in blood pressure. When you take a sartan drug like olmesartan, the hormone can’t work as well as usual and your blood pressure gets lower, which is useful in the treatment of hypertension.

Brand Names and Doses

Brand Dose IconOlmesartan is the genic name, the name of the active drug found in the medication, but you might be more familiar with the brand name, Olmetec. There are two different doses of this medication available: 20 mg and 40 mg.

Most people begin with the lower 20 mg dose and after about two months the dose can be increased to 40 mg if the blood pressure is still high. This method helps to reduce initial side effects that may occur with this medicine.

Olmesartan is also available in combination other medications.

Sevikar is the brand name of the combination medication with olmesartan and a calcium channel blocker, amlodipine. It is available in three different doses:

  • Olmesartan 20 mg / Amlodipine 5 mg
  • Olmesartan 40 mg / Amlodipine 5 mg
  • Olmesartan 40 mg / Amlodipine 10 mg

Olmetec plus is the brand name of the combination medication with olmesartan and a diuretic drug, hydrochlorothiazide. It is available in three different doses:

  • Olmesartan 20 mg / Hydrochlorothiazide 12.5 mg
  • Olmesartan 40 mg / Hydrochlorothiazide 12.5 mg
  • Olmesartan 40 mg / Hydrochlorothiazide 25 mg
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What type of drug is it?

Drug Type IconOlmesartan is a type of drug called a sartan, which is a class of drug, also sometimes known as angiotensin receptor blockers (ARB) or angiotensin receptor antagonists (ARA), that work in the same way. Other medicines in the same class are:

How does it work?

How it works IconOlmesartan works by blocking the angiotensin II hormone from binding to a receptor in the body, stopping certain reactions that usually increase the pressure of the blood.

In a healthy person, angiotensin II helps to keep the balance of blood pressure just right. If it gets too low, the body produces more angiotensin II to increase its effects and help to increase the blood pressure slightly. The muscles around the blood vessels contract, making the passageway narrower, and the kidneys reabsorb more water, increasing the amount of blood in the body. With more blood travelling through thinner vessels, the blood pressure is going go up and restore the balance in the body.

When you take olmesartan, angiotensin II doesn’t work as well to activate the receptor. As a result, the opposite effect is seen:

  • The muscles around your blood vessels relax, creating more space for the blood passing through.
  • Your kidneys reabsorb less water and you excrete more in your urine, leading to less blood in your circulation.

Less blood pumping around larger blood vessels means the pressure will be lower. If you think of it like a plumbing system, there will be less stress for your heart to pump blood around the body.

Side Effects

Side Effects IconSartans affect the body in various ways and there are several side effects that may occur when you take olmesartan.

Low blood pressure (hypotension)

The most common side effects happen when irbesartan is working too well and you end up with low blood pressure. You might notice:

  • Headache
  • Tiredness
  • Dizziness
  • Flushing

This is most common when you first start taking olmesartan or after a dose increase. It usually gets better within a few days as your body gets used to the medication. If you still notice the effects after a week, your dose may be too high and your blood pressure too low as a result. It’s easy to check your blood pressure at a pharmacy and ask your doctor if you need to change or reduce the dose.

Excess Potassium (Hyperkalaemia)

Olmesartan causes more water to be excreted in the urine than usual, which can upset the balance of potassium in your body. Less potassium is excreted and it can build up, making you feel tired and you may have muscle weakness. If you notice these symptoms, you can ask your doctor for a blood test to check if you have high potassium levels and decide if you should change medication.


Some people also get a dry cough when they take olmesartan. If this affects you, you can talk to your doctor about alternative medication options for hypertension.


Cautions IconThere are a couple of things you should be aware of before you start taking olmesartan, which are listed below:

Angioedema – Swelling of your mouth and face, which is particularly dangerous if the airways become blocked. You should see a doctor as soon as possible if this occurs.

Renal Impairment – Changes to the kidney function can increase the risk of renal impairment, especially when used with other medications such as NSAIDS and diuretics.  If you have poor kidney function, an alternative medication for hypertension is likely to be safer.

Stopping Suddenly – You may get rebound hypertension with even higher blood pressure than before if you suddenly stop taking the medication. This is because your body has adapted to taking the drug each day and, if you want to stop,  it is best to gradually reduce the dose over a few weeks.

Drug Interactions

Drug Interactions IconLithium + Olmsartan Interaction

Olmesartan can decrease the amount of lithium that is excreted from the body and increase the risk of side effects. The dose of lithium can be reduced to help manage this, or a different antihypertensive medication can be used.

Loop Diuretic + Olmesartan Interaction

Taking a loop diuretic drug with olmesartan can increase the risk of renal impairment and blood pressure that is too low, particularly for the first few doses. It is best to take a lower dose or to stop taking the loop diuretic for a few days when beginning olmesartan.

NSAID + Olmesartan Interaction

NSAIDs and olmesartan can sometimes be used together in young and otherwise healthy patients, but it might not work as well to reduce your blood pressure and can lead to renal impairment.

Thiazide Diuretic + Olmesartan Interaction

Taking a thiazide diuretic and olmesartan together increases the risk of renal impairment and blood pressure that is too low, particularly for the first few doses. Using a lower dose is okay for some people but the combination is not recommended for others – you should talk to your doctor if you’re worried.

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Pregnancy and Breastfeeding

Pregnancy IconOlmesartan should not be used by women who are pregnant or planning to become pregnant because they can cause birth defects early in the pregnancy and may cause renal dysfunction of the fetus later in the pregnancy.

It is not recommended to take it while breastfeeding because there is limited research data available and we don’t know if it is safe.

How Does Olmesartan Work?

About the author


Yolanda is a passionate medical writer who loves to help people understand how health and different treatments work. After graduating in Pharmacy in Australia, she moved to Italy to study the Mediterranean way of life and continue learning about health and medicine.


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