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Furosemide, sometimes prescribed under the brand name Lasix, is a potent diuretic, or water pill.

It is used to treat high blood pressure as well as a number of serious conditions in which fluid builds up in body tissues

Side Effects and Interactions

People on furosemide may feel dizzy or faint if they stand up rapidly. Older people especially may need to take care to avoid falling when they first get up.

Increased frequency of urination is common but may be less bothersome if you take your medicine at breakfast rather than at night.

Other adverse reactions to be alert for include rash, itching, sensitivity to sunlight leading to sunburn, ringing in the ears, nausea, diarrhea or constipation, muscle cramps, hearing loss, unexplained sore throat with fever, bruising, blurred vision, loss of appetite, increases in blood sugar, headache, gout and tingling or numbness in hands or feet.

Report any symptoms to your physician promptly.

Furosemide can interact with a number of other medications. Lanoxin and other digitalis heart medicines may cause abnormal heart rhythms if potassium levels are decreased by diuretics.

Indocin, Clinoril, ibuprofenDilantin and activated charcoal may interfere with the effectiveness of furosemide.

At high doses, furosemide can increase the activity of the blood thinner Coumadin.

Adding furosemide to thiazide diuretics may deplete the body rapidly of fluid and minerals, and calls for careful monitoring.

Licorice  can greatly increase potassium loss in people taking Lasix.

Lasix and other potassium-wasting diuretics are probably incompatible with the herb cascara sagrada, at least if it were used more than very occasionally. Cascara sagrada, like other strong laxatives, may reduce the absorption of other medicines taken orally.

Aloe (latex) might be dangerous for anyone taking Lasix because of an additive effect. It should be avoided in such situations.

Check with your doctor and pharmacist to make sure furosemide is safe in combination with any other drugs or herbs you take.

Special Precautions

Like many diuretics, furosemide depletes the body of potassium and other important minerals. People taking this medicine may need to include potassium-rich foods in their diet.

Vegetables such as potatoes, beets, brussels sprouts, spinach, cabbage, broccoli, carrots, peppers and squash are good sources of potassium. So are apricots, strawberries, bananas, oranges, peaches and plums.

Most fish also provide good quantities of this mineral.

Some people may not be able to maintain adequate potassium levels even with a diet rich in fish, fruits and vegetables.

Periodic blood tests are crucial to monitor potassium levels in the body. If such a test shows that potassium levels are low, your physician may recommend you cook with a potassium-based salt substitute or he may prescribe a potassium supplement.

Taking the Medicine

Furosemide is absorbed most completely when it is taken on an empty stomach.

This medication may cause stomach upset, however, which tends to be less of a problem when it is taken with food or milk. As the dose should be adjusted individually, with the help of blood tests, let your doctor know if you will change the way you take this drug.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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