Generic Name: furosemide (fur OH se mide)
Brand Name: Lasix, Diaqua-2, Lo-Aqua
Medically reviewed by Sophia Entringer, PharmD. Last updated on Dec 25, 2020.
What is Lasix?
Lasix (furosemide) is a loop diuretic (water pill) that prevents your body from absorbing too much salt. This allows the salt to instead be passed in your urine.
Lasix is also used to treat high blood pressure (hypertension).
You should not use Lasix if you are unable to urinate.
Do not take more Lasix than your recommended dose. High doses of furosemide may cause irreversible hearing loss.
Before using Lasix, tell your doctor if you have kidney disease, enlarged prostate, urination problems, cirrhosis or other liver disease, an electrolyte imbalance, high cholesterol, gout, lupus, diabetes, or an allergy to sulfa drugs.
Tell your doctor if you have recently had an MRI (magnetic resonance imaging) or any type of scan using a radioactive dye that is injected into your veins. Do not take more of this medication than is recommended. High doses of furosemide may cause irreversible hearing loss. If you are being treated for high blood pressure, keep using this medication even if you feel fine. High blood pressure often has no symptoms.
Before taking this medicine
You should not use Lasix if you are allergic to furosemide, or:
if you are unable to urinate.
To make sure Lasix is safe for you, tell your doctor if you have:
enlarged prostate, bladder obstruction, urination problems;
cirrhosis or other liver disease;
an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);
high cholesterol or triglycerides (a type of fat in the blood);
a thyroid disorder;
sulfa drug allergy.
Tell your doctor if you have an MRI (magnetic resonance imaging) or any type of scan using a radioactive dye that is injected into your veins. Both contrast dyes and furosemide can harm your kidneys.
It is not known whether Lasix will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.
Furosemide can pass into breast milk and may harm a nursing baby. This medicine may also slow breast milk production. Tell your doctor if you are breast-feeding a baby.
How should I take Lasix?
Take Lasix exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.
Do not take more than your recommended dose. High doses of furosemide may cause irreversible hearing loss.
Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
Lasix will make you urinate more often and you may get dehydrated easily. Follow your doctor's instructions about using potassium supplements or getting enough salt and potassium in your diet.
While using Lasix, you may need frequent blood tests.
Keep using this medicine as directed, even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life.
If you need surgery, tell the surgeon ahead of time that you are using Lasix.
Store at room temperature away from moisture, heat, and light. Throw away any Lasix oral solution (liquid) 90 days after opening the bottle, even if it still contains unused medicine.
What happens if I miss a dose?
Lasix is sometimes used only once, so you may not be on a dosing schedule. If you are using the medication regularly, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include feeling very thirsty or hot, heavy sweating, hot and dry skin, extreme weakness, or fainting.
What to avoid
Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.
Avoid becoming dehydrated. Follow your doctor's instructions about the type and amount of liquids you should drink while you are taking Lasix.
Drinking alcohol with this medicine can cause side effects.
Lasix side effects
Get emergency medical help if you have signs of an allergic reaction to Lasix: (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).
Call your doctor at once if you have:
ringing in your ears, hearing loss;
easy bruising, unusual bleeding;
sudden weakness or ill feeling, fever, chills;
painful or difficult urination;
numbness, tingling, or burning pain;
a light-headed feeling, like you might pass out;
high blood sugar - increased thirst, increased urination, dry mouth, fruity breath odor;
signs of liver or pancreas problems - loss of appetite, upper stomach pain (that may spread to your back), nausea or vomiting, dark urine, jaundice (yellowing of the skin or eyes);
kidney problems - little or no urination, swelling in your feet or ankles, feeling tired or short of breath; or
signs of an electrolyte imbalance - dry mouth, increased thirst, mood changes, weakness, drowsiness, lack of energy, muscle pain, fast heartbeats, feeling restless, nausea, vomiting.
Common Lasix side effects may include:
numbness or tingling;
headache, dizziness; or
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect Lasix?
Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.
If you also take sucralfate, take your furosemide dose 2 hours before or 2 hours after you take sucralfate.
Tell your doctor about all your current medicines and any you start or stop using, especially:
cancer medicine, such as cisplatin;
heart or blood pressure medicine; or
another diuretic, especially ethacrynic acid.
This list is not complete. Other drugs may interact with furosemide, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
Frequently asked questions
- Are losartan and losartan potassium the same drug or two different ones?
- How long after taking Lasix would you expect to urinate?
- Can you take Lasix for weight loss?
More about Lasix (furosemide)
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Compare Alternatives
- Support Group
- Pricing & Coupons
- En Español
- 49 Reviews
- Generic Availability
- Drug class: loop diuretics
- FDA Alerts (1)
Related treatment guides
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Lasix only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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