Losartan is an angiotensin II receptor blocker (ARB) that belongs to the “Heart & Blood Pressure” therapeutic class. It is available as oral pills in strengths of 25 mg, 50 mg, and 100 mg. In Hong Kong, Losartan is a prescription-only medication regulated by the Department of Health.
Losartan selectively blocks the angiotensin II type 1 (AT₁) receptor. Angiotensin II is a hormone that narrows blood vessels and stimulates the release of aldosterone, which increases fluid retention. By preventing angiotensin II from binding to its receptor, Losartan:
The onset of blood-pressure reduction typically occurs within 1-2 hours after a dose, with the maximum effect reached after about 2 weeks of regular use. Losartan has a half-life of roughly 2 hours, but an active metabolite (EXP-3174) extends its antihypertensive action for up to 24 hours.
Losartan is approved in Hong Kong and many other jurisdictions for the following indications:
These uses are supported by large clinical trials and regulatory labeling.
These effects are generally mild, transient, and often improve with continued therapy.
If any of these serious symptoms occur, patients should seek immediate medical care.
Because interaction data are extensive, patients should disclose all prescription medicines, over-the-counter drugs, herbal products, and supplements to their healthcare provider before starting Losartan.
Standard dosing:
Initiate with 50 mg once daily for hypertension; the dose may be increased to 100 mg once daily based on blood-pressure response.
For heart failure, the typical starting dose is 12.5 mg once daily, titrated up to 150 mg daily (often divided into two doses).
In diabetic nephropathy, 50 mg once daily is a common starting point, with adjustments as needed.
Special populations:
Renal impairment: Begin with 25 mg once daily; monitor renal function and potassium.
Elderly: Consider starting at 25 mg once daily, especially if multiple antihypertensives are already prescribed.
Administration: Swallow the tablet whole with a glass of water. It may be taken with or without food.
Missed dose: Take the missed tablet as soon as remembered unless it is almost time for the next scheduled dose; in that case, skip the missed dose and continue the regular schedule. Do not double up.
Overdose: Symptoms may include severe hypotension, fainting, and rapid heart rate. Seek emergency medical attention; supportive care and monitoring are the mainstays of treatment.
Discontinuation: Losartan can be stopped abruptly, but clinicians often recommend a gradual taper when used for heart failure to avoid rebound hypertension.
This article provides educational information about Losartan and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
If dizziness occurs, sit or lie down until it passes and avoid sudden changes in posture. Notify your healthcare provider, as your dose may need adjustment or an alternative medication may be considered.
Losartan is often combined with other antihypertensives such as calcium-channel blockers or thiazide diuretics to achieve better control. Your doctor will determine safe combinations based on your overall regimen.
Mild hepatic impairment does not usually require a dose change, but severe liver disease is an absolute contraindication. Liver function should be assessed before initiating therapy.
Both classes block the renin-angiotensin system, but Losartan (an ARB) directly blocks the receptor, while ACE inhibitors block the enzyme that forms angiotensin II. ARBs are less likely to cause a persistent cough, a common side effect of ACE inhibitors.
Losartan does not directly alter glucose metabolism, but it can improve kidney outcomes in patients with type 2 diabetes, potentially supporting overall diabetes management.
Yes, but keep the medication in its original labeled container, carry a copy of the prescription, and be aware of any import restrictions or documentation requirements in the destination country.
Supplements containing potassium, such as potassium chloride or certain herbal products, can increase the risk of hyperkalemia. Discuss all supplements with your healthcare provider.
In Hong Kong, generic Losartan 50 mg tablets commonly bear the imprint “LOS 50 MG” (manufacturer-specific). If the tablet appearance differs from what you expect, verify its authenticity with your pharmacist.
Losartan does not produce tolerance; its effectiveness remains stable when taken consistently at the prescribed dose.
A modest reduction can be seen within a few days, but the full therapeutic effect may require up to 2 weeks of regular dosing. Regular monitoring helps determine when the target pressure is achieved.
