Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar) is a combined antihypertensive drug composed of losartan potassium (an angiotensin II receptor blocker, ARB) and hydrochlorothiazide (a diuretic). It is used for the treatment of hypertension and for reducing the risk of stroke in patients with left ventricular hypertrophy.

What Are the Side Effects of Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar)?

Common Side Effects

Nervous system: Dizziness (5.7%), headache.

Respiratory system: Upper respiratory tract infection (6.1%), cough.

Musculoskeletal system: Back pain (2.1%), muscle spasms.

Metabolic abnormalities: Hypokalemia (6.7%), hyperkalemia (0.4%), hyperuricemia.

Digestive system: Nausea, abdominal pain.

Other occasional reactions include rash, blurred vision (transient myopia associated with hydrochlorothiazide), and blood glucose fluctuations.

Severe Side Effects of Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar) That Require Vigilance

Fetal Toxicity

Risk: Use during the second and third trimesters of pregnancy may cause fetal renal failure, skull hypoplasia, or even fetal death.

Measure: Discontinue the drug immediately if pregnancy is detected, and switch to an alternative antihypertensive regimen.

Hypotension and Electrolyte Imbalance

High-risk populations: Patients with dehydration or salt depletion, the elderly, and patients with renal impairment.

Manifestations: Severe hypotension; hyponatremia/hypokalemia/hypomagnesemia (associated with hydrochlorothiazide); or hyperkalemia (associated with losartan).

Monitoring: Correct blood volume before medication, and regularly monitor electrolytes and renal function.

Acute Renal Failure

Triggers: Renal artery stenosis; concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs, e.g., ibuprofen); or dual renin-angiotensin system (RAS) blockade (e.g., combined use with angiotensin-converting enzyme inhibitors, ACEIs).

Management: If renal function deteriorates, reduce the dose or discontinue the drug.

Allergic Reactions

Manifestations: Angioedema (risk of laryngeal edema), anaphylactic shock, drug-induced hepatitis.

Note: Use with caution in patients allergic to sulfonamides (hydrochlorothiazide is a sulfonamide derivative).

Other Severe Reactions

Acute angle-closure glaucoma: Sudden vision loss and eye pain require immediate drug discontinuation and emergency ophthalmological treatment.

Rhabdomyolysis: Rare, but attention should be paid to symptoms of myalgia/muscle weakness.

Precautions for Administration of Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar)

Dose Adjustment

Hypertension: The initial dose is 50/12.5 mg once daily, with a maximum dose of 100/25 mg once daily.

Left ventricular hypertrophy: Start at 50/12.5 mg, and gradually titrate to 100/25 mg.

Hepatic and renal impairment: Avoid use in patients with severe hepatic impairment (no 25 mg initial dosage form available); the safety in patients with a creatinine clearance < 30 mL/min has not been established.

Special Populations

Elderly patients: More prone to hypotension and changes in renal function, requiring close monitoring.

Black patients: The benefit of stroke prevention in those with left ventricular hypertrophy may not be significant.

Patient Education

Avoid alcohol consumption or strenuous exercise to prevent hypotension.

Report any edema, dyspnea, or persistent dizziness.

Regularly monitor blood pressure, serum potassium levels, and renal function.