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

Serious 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.

Measures: Discontinue the drug immediately once pregnancy is detected, and switch to another antihypertensive regimen.

Hypotension and Electrolyte Imbalance

High-risk groups: Patients with dehydration or salt deficiency, elderly patients, 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 test electrolytes and renal function.

Acute Renal Failure

Triggers: Renal artery stenosis; concurrent use of NSAIDs (e.g., ibuprofen); or dual renin-angiotensin system (RAS) blockade (e.g., concurrent use of ACE inhibitors).

Management: Reduce the dose or discontinue the drug if renal function deteriorates.

Allergic Reactions

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

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

Other Serious Reactions

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

Rhabdomyolysis: Rare, but attention should be paid to symptoms such as myalgia or muscle weakness.

Precautions for Using Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar)

Dosage 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 with 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 of < 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 patients with left ventricular hypertrophy may not be significant.

Patient Education

Avoid alcohol consumption or strenuous exercise to prevent hypotension.

Report any edema, difficulty breathing, or persistent dizziness.

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