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Losartan is an angiotensin II receptor blocker (ARB) that helps relax blood vessels to lower blood pressure and improve blood flow.

Last Modified: 10 May 2024

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What is Losartan? 

Losartan is an angiotensin II receptor blocker (ARB) that helps relax blood vessels to lower blood pressure and improve blood flow.  

Losartan, a biphenyl tetrazole derivative, is synthesized to block angiotensin II receptors, which are responsible for vasoconstriction. 

Global Name

Generic name: Losartan
Brand names: Cozaar, Hyzaar, Zaart, Lortaan, Losar


What is Losartan used for? 

Losartan is primarily used to treat high blood pressure (hypertension), reduce stroke risk in patients with heart disease, and protect kidney function in diabetic patients. 

How do you use Losartan? 


Losartan is available in tablet form.

Dosage information: 

  • Adults with Hypertension: Start with 50 mg once daily, may increase to 100 mg once daily based on blood pressure response. 
  • Children aged 6 years and older with Hypertension: Dosage must be individualized. 
  • Elderly: No initial dosage adjustments necessary. 


  • Children: Suitable for children 6 years and older, with careful dosing. 
  • Adults: Suitable for adults with hypertension or heart disease. 
  • Elderlies: Suitable without initial dosage adjustment; renal function and serum potassium (K) monitoring advised. 


Is there anyone who can’t take Losartan? 

  • Children: Not recommended for children under 6 years old. 
  • Adults:  Not for use in patients with known allergy to losartan or any of its components, bilateral renal stenosis, critically declining renal function, and history of angioedema 
  • Pregnancy and Lactation: Not recommended due to potential harm to the fetus. 


Any warnings and precautions : 

Monitor blood pressure, kidney function and electrolytes regularly. 


Food and Drug Interactions: 

  • Losartan may interact with other blood pressure medications, potassium supplements, NSAIDs, or drugs that affect kidney function. 
  • Consumption of grapefruit or grapefruit juice may decrease blood levels of losartan in certain susceptible patients (due to enzymatic inhibition in the intestines) 

Side Effects

Possible side effects include dry cough, weakness, chest pain, diarrhea, hypoglycemia and fatigue.

Pharmacist Tips

  • Dosing Time: Take Losartan at the same time each day to maintain an even level in your bloodstream. 
  • With or Without Food: Losartan can be taken with or without food, but consistency can help with habit formation. 
  • Kidney Function: Patients with kidney issues should discuss dosing adjustments with a healthcare provider. 
  • Blood Pressure Monitoring: Regularly monitor blood pressure to ensure the medication is effective. 
  • Storage Information: Store at room temperature away from moisture, heat, and light. 
  • Handling Instructions: Handle tablets with clean hands and only remove a dose from the packaging when ready to take it. 


Where is Losartan available in Hong Kong?

Losartan is a prescription medication that can be prescribed by healthcare providers then bought in pharmacies. 



Can Losartan be taken for a long time?

Losartan can be a maintenance medication especially for hypertension under medical supervision. 

Should I take Losartan in the morning or at night?

It can be taken at any time of day, but it is important to take it at the same time each day.

Is Losartan available for purchase over the counter?

No, Losartan requires a prescription from a healthcare provider. 

Why does Losartan cause back pain?

Losartan may cause back pain as a potential side effect, although the exact reason is not fully understood. Possible explanations include muscle cramp/ spasm , potential renal effects, and individual sensitivity. If you experience back pain while taking Losartan or any medication, it is important to consult with your healthcare professional for evaluation and guidance. 

This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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