Do NOT use Lasix if:

• you are allergic to any ingredient in Lasix
• you are unable to urinate
• you are taking ethacrynic acid.

Contact your doctor or health care provider right away if any of these apply to you.

Some medical conditions may interact with Lasix. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
• if you have allergies to medicines, foods, or other substances
• if you have fluid in your abdomen (ascites), hearing problems, liver disease, diabetes, low urine output, kidney problems, lupus, gout, abnormal blood electrolyte levels, high blood uric acid levels, or the blood disease porphyria
• if you have had a heart attack, are dehydrated, or are on a low-salt diet.

Some medicines may interact with Lasix. Tell your health care provider if you are taking any other medicines, especially any of the following:

• Corticosteroids (eg, prednisone) or corticotropin (ACTH) because the risk of low blood potassium levels may be increased
• Barbiturates (eg, phenobarbital) or narcotics (eg, codeine) because the risk of dizziness upon standing may be increased
• Aminoglycosides (eg, gentamicin), amphotericin B, angiotensin-converting enzyme (ACE) inhibitors (eg, captopril), cyclosporine, ethacrynic acid, tacrolimus, or vancomycin because serious side effects to the kidneys (decreased ability to urinate) or ears (hearing loss) may occur
• Chloral hydrate because side effects, such as excessive sweating, rapid heartbeat, and changes in blood pressure, may occur
• Nonsteroidal anti-inflammatory drugs (NSAIDs) (eg, ibuprofen, indomethacin) because they may decrease Lasix's effectiveness
• Digoxin, lithium, medicines for high blood pressure, salicylates (eg, aspirin), or succinylcholine because the risk of their side effects may be increased by Lasix
• Norepinephrine or tubocurarine because their effectiveness may be decreased by Lasix.

This may not be a complete list of all interactions that may occur. Ask your health care provider if Lasix may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

Important safety information:

• Lasix may cause dizziness or blurred vision. These effects may be worse if you take it with alcohol or certain medicines. Use Lasix with caution. Do not drive or perform other possible unsafe tasks until you know how you react to it.
• Lasix may cause dizziness, lightheadedness, or fainting; alcohol, hot weather, exercise, or fever may increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects.
• Diabetes patients - Lasix may affect your blood sugar. Check blood sugar levels closely. Ask your doctor before you change the dose of your diabetes medicine.
• Tell your doctor or dentist that you take Lasix before you receive any medical or dental care, emergency care, or surgery.
• Your doctor may also prescribe a potassium supplement while you take Lasix. Check with your doctor before you use a salt substitute or other product that has potassium in it.
• Lasix is a strong diuretic. Using too much of this drug can lead to serious water and mineral loss. Therefore, it is important that you be monitored by your doctor. Promptly notify your doctor if you become very thirsty, have a dry mouth, become confused, or develop muscle cramps/weakness.
• Patients who take medicine for high blood pressure often feel tired or run down for a few weeks after starting treatment. Be sure to take your medicine even if you may not feel "normal." Tell your doctor if you develop any new symptoms.
• If you have high blood pressure, do not use nonprescription products that contain stimulants. These products may include diet pills or cold medicines. Contact your doctor if you have any questions or concerns.
• Lasix may cause you to become sunburned more easily. Avoid the sun, sunlamps, or tanning booths until you know how you react to Lasix. Use a sunscreen or wear protective clothing if you must be outside for more than a short time.
• Lab tests, including blood pressure and complete blood counts, may be performed while you use Lasix. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
• Use Lasix with caution in the elderly; they may be more sensitive to its effects, especially dehydration.
• Caution is advised when using Lasix in children; they may be more sensitive to its effects.
• Pregnancy and breast-feeding: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Lasix while you are pregnant. Lasix is found in breast milk. If you are or will be breast-feeding while you use Lasix, check with your doctor. Discuss any possible risks to your baby.

All medicines may cause side effects, but many people have no, or minor, side effects.

Check with your doctor if any of these most common side effects persist or become bothersome:

Dizziness; lightheadedness; sensitivity to sunlight.

Seek medical attention right away if any of these severe side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); calf pain or tenderness; confusion; dark urine; decreased or persistent increased urination; drowsiness; dry mouth; fast or irregular heartbeat; fever, chills, or sore throat; hearing decrease or loss; muscle pain/cramps/weakness; restlessness; ringing in the ears; severe or persistent nausea, vomiting, or dizziness; shortness of breath; sluggishness; stomach pain; unusual bleeding or bruising; unusual thirst or hunger; unusual tiredness or weakness; vein inflammation; yellow vision; yellowing of the skin or eyes.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.