Summary

Lisinopril and furosemide can be used together but require careful monitoring due to increased risk of hypotension, electrolyte imbalances, and potential kidney function impairment. This combination is commonly prescribed for heart failure and hypertension management.

Introduction

Lisinopril is an ACE (angiotensin-converting enzyme) inhibitor primarily used to treat high blood pressure, heart failure, and protect kidney function in diabetic patients. Furosemide is a loop diuretic (water pill) that helps remove excess fluid from the body by increasing urine production, commonly prescribed for heart failure, edema, and hypertension. Both medications are frequently used together in cardiovascular medicine to manage fluid retention and blood pressure control.

Mechanism of Interaction

The interaction between lisinopril and furosemide occurs through their complementary mechanisms of action on blood pressure and fluid balance. Lisinopril blocks the conversion of angiotensin I to angiotensin II, leading to vasodilation and reduced aldosterone secretion. Furosemide inhibits sodium and chloride reabsorption in the kidney's loop of Henle, promoting diuresis. When used together, both drugs can cause additive hypotensive effects, and furosemide-induced volume depletion can enhance the blood pressure-lowering effects of lisinopril, potentially leading to excessive hypotension.

Risks and Symptoms

The primary risks of combining lisinopril and furosemide include symptomatic hypotension (especially first-dose hypotension), electrolyte imbalances (particularly hyponatremia, hypokalemia, and hypomagnesemia), acute kidney injury due to volume depletion, and dehydration. Elderly patients and those with pre-existing kidney disease are at higher risk. The combination may also increase the risk of lithium toxicity if the patient is taking lithium, as both drugs can reduce lithium clearance.

Management and Precautions

Monitor blood pressure regularly, especially when initiating therapy or adjusting doses. Check kidney function (serum creatinine, BUN) and electrolytes (sodium, potassium, magnesium) before starting treatment and periodically thereafter. Start with lower doses and titrate gradually. Ensure adequate hydration and advise patients to rise slowly from sitting or lying positions to prevent orthostatic hypotension. Consider temporary discontinuation of one or both medications during illness causing dehydration or vomiting. Regular follow-up appointments are essential to assess therapeutic response and monitor for adverse effects.

Lisinopril interactions with food and lifestyle

Lisinopril may interact with potassium-containing salt substitutes and potassium supplements, potentially leading to dangerous elevations in blood potassium levels (hyperkalemia). Patients should consult their healthcare provider before using salt substitutes or taking potassium supplements while on lisinopril. Alcohol consumption may enhance the blood pressure-lowering effects of lisinopril, potentially causing excessive drops in blood pressure, dizziness, or fainting. Patients should limit alcohol intake and monitor for symptoms of low blood pressure when drinking alcohol while taking lisinopril.

Furosemide interactions with food and lifestyle

Furosemide should be taken with food or milk to reduce stomach upset. Alcohol consumption should be limited as it can increase the risk of dehydration and low blood pressure when combined with furosemide. Patients should maintain adequate fluid intake unless specifically restricted by their healthcare provider, as furosemide can cause dehydration. Salt substitutes containing potassium should be used cautiously, as furosemide can affect potassium levels. Excessive sun exposure should be avoided as furosemide may increase sensitivity to sunlight.