Medicines & Supplements A to Z > Olmesartan


Last updated on 24/03/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Olmesartan 


BRAND NAME(S) IN HONG KONG: Azoren (Contains Olmesartan and Amlodipine), Esatec, Olmecor, Olmesartan Sandoz, Olmetec 安脈思, Olmetec Plus (Contains Olmesartan and Hydrochlorothiazide)

DRUG CLASS: Angiotensin II receptor blocker; Antihypertensive 

USED FOR: High blood pressure 

OTHER DRUGS IN THE SAME CLASS: Azilsartan, Candesartan, Eprosartan, Irbesartan, Losartan, Telmisartan, Valsartan

AVAILABLE DOSAGE FORMS: 10mg, 20mg, 40mg (tablets)

What is Olmesartan for?

Olmesartan belongs to a class of medications called angiotensin receptor blockers (ARBs), just like Losartan. ARBs block the substances that constrict the blood vessels and hence more blood and oxygen can reach the heart. Olmesartan is therefore commonly used to treat high blood pressure in adults and children aged 6 years or above, especially when medications such as Lisinopril or Ramipril (angiotensin converting enzyme inhibitor) cannot be used.

How to use it?

Olmesartan is given orally as tablets. The dose for high blood pressure in different age groups is listed below: 

Initially, take 20 mg once per day. Your doctor will assess your response and adjust the dose every 4-6 weeks up to 40 mg once daily. 

Children ≥ 6 years
Start with 10-20 mg once per day. The dose may be increased to 40 mg once daily after 2 weeks if necessary. 

What are the side effects of Olmesartan?

Common side effects of Olmesartan include diarrhea, dizziness, headache, high potassium levels, low blood pressure, and kidney impairment. If you have intravascular volume depletion, for example, those taking high-dose other blood pressure-lowering drugs, you may also experience postural hypotension, that is your blood pressure falls when you stand up from sitting or lying down.

Who should not take Olmesartan?

– People with an allergy to Olmesartan or any formulation ingredient.
– Patients who are on Aliskiren and have diabetes.

Pharmacist Tips:

– Inform your doctor or pharmacist immediately if you know you are pregnant while on this medication.
– Avoid alcohol while you are taking Olmesartan to reduce dizziness.
– If you experience postural hypotension, get up slowly from lying or sitting positions or sit down until you feel better. 

Common dosing schedule:
You can take Olmesartan with or without food. 

Take the first dose at bedtime to avoid dizziness. You can take it at any time of day afterward. Take the drug at the same time every day.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Olmesartan may interact with:
– Angiotensin-converting enzyme inhibitor, e.g. Captopril, Enalapril
– Nonsteroidal anti-inflammatory drugs, e.g. Ibuprofen, Naproxen
– Other angiotensin II receptor blockers, e.g. Telmisartan, Valsartan
Potassium supplements
– Spironolactone

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Olmesartan in Hong Kong?

In Hong Kong, Olmesartan is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Olmesartan in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.