Furosemide Side Effects

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Answer the side-effect intent for furosemide without diagnosing; distinguish common from serious reactions and give safe next-step/reporting guidance.

What is furosemide?

Furosemide contains the active ingredient Furosemide.

• Active ingredient — Furosemide
• Registration number — 46/18.1/0017
• Registration holder — Unimed Healthcare (Pty) Ltd

It is approved for:

• FUROSEMIDE 40 UNIMED contains the active ingredient furosemide
• Furosemide one of a group of medicines called diuretics (water tablets)
• Your doctor has prescribed S3 □ FUROSEMIDE 40 UNIMED tablets to treat a condition called oedema where there is too much water in your body
• Diuretics are used to remove extra fluid in you body by making you pass urine

Common side effects of furosemide

Not everyone gets side effects. The effects below are those listed in the South African approved leaflet, grouped using the leaflet’s own frequency wording.

Frequent side effects

• low blood pressure (symptoms include dizziness, light headedness, nausea)
• light headedness when getting up from a lying or sitting position (a form of low blood pressure)
• increase number of red blood cells and the other components of blood (haemoconcentration)
• too low levels of sodium in your blood (shortness of breath, headache, dizziness, confusion, coma)
• too low levels of potassium in your blood (abnormal or slow heart rate, low blood pressure, cramps, weakness)
• decreased levels of chloride, calcium, magnesium in your blood
• muscle cramps, confusion, and numbness caused by decreased levels of chloride in the blood leading to changes in the pH of the blood (metabolic alkalosis)
• increased levels of creatinine, cholesterol or triglyceride levels in your blood (noticed on a blood test)
• increased uric acid levels, which may cause gout attacks (warmth, pain swelling in a joint, usually the big toe)
• an increase in the volume of urine you produce

Less frequent side effects

• decrease in HDL-cholesterol (seen on a blood test)
• diabetes may occur or get worse
• increased blood glucose levels where symptoms may include thirst, hunger, frequent urination, headaches, trouble concentrating, blurred vision, weight loss
• psychiatric disorders
• headache, pins and needle sensation, coma as a result of high blood sugar levels, confusion, dizziness
• yellow or blurred vision, visual disturbance
• ringing in the ears (especially in people who already have problems with their kidneys), loss of hearing, dizziness, deafness, hearing problems
• irregular heartbeat, weak pulse
• cough or hoarseness
• severe stomach pain with nausea and vomiting, diarrhoea, loss of appetite, anorexia, black, tarry stools, blood in stools, dryness of the mouth, increased thirst, dehydration, changes in bowel movements, constipation
• pin-point red spots on skin; skin rash or hives, increased sensitivity of the skin to sunlight, large itchy fluid-filled blisters (bullous pemphigoid)
• joint pain, lower back or side pain, calf muscle cramps, muscle weakness
• blood in the urine, painful or difficult urination, urine leakage (urinary incontinence)
• increase in liver transaminases (seen on a blood test)
• fever or chills, unusual tiredness or weakness, general sense of not feeling well

Frequency not known side effects

• worsening of systemic lupus erythematosus
• worsening of metabolic acidosis in patient with liver scarring (cirrhosis), may experience muscle cramps, confusion, and numbness
• lichenoid reactions that manifest as small, itchy, reddish-purple, uneven changes to the skin, genitals or in the mouth
• unusual muscle movements, such as jerking, twitching or muscle spasm, muscle cramps (tetany)
• muscle injury (rhabdomyolysis)
• problems with circulation causing vertigo (spinning sensation or loss of balance), visual impairment, feeling pressure in your head
• increase in sodium and chloride in the urine (noticed on a urine test)

Serious side effects and warning signs

This leaflet does not set out a separate list of serious side effects. The general warning signs below apply to any medicine.

General warning signs that apply to any medicine

How long can side effects last?

How long a side effect lasts depends on the effect, the product, how long it has been used, and the person. Some effects ease within days as the body adjusts. Others continue for as long as the product is used. A few can persist after stopping, and some need review rather than waiting.

• Settling effects — mild effects that ease over the first days or weeks of use
• Ongoing effects — effects that continue while the product is being used and improve after stopping
• Persistent effects — effects that continue after stopping and need medical review
• Delayed effects — effects that appear after weeks or months rather than immediately

Which of these applies to a particular effect is a clinical question. If a side effect is not settling, is getting worse, or is affecting your daily life, that is worth a conversation with a pharmacist or doctor regardless of how long it has been going on.

Factors that may affect side effects

The approved leaflet identifies the following cautions and factors.

Do not use it at all if

• are hypersensitive (allergic) to furosemide, or any of the other ingredients of FUROSEMIDE 40 UNIMED (listed in section 6)
• are hypersensitive (allergic) to sulfur containing medicines
• have increased urea in the blood (noticed on a blood test but you may experience fatigue, nausea, itching, and neurological issues), very low amount of urine or no urine, due to kidney problems
• have severe kidney failure
• have low potassium or low sodium or you have any disorder of body chemicals (this may make you feel weak, apathetic or have muscle spasms), until your condition has improved
• have low blood volume with or without low blood pressure
• have dehydration (you have lost lots of body fluid for example by suffering from severe diarrhoea or being sick)
• are in a coma caused by liver problems, until your condition has improved
• are breastfeeding your baby or you are pregnant
• are a woman who has started menopause and have the condition known as osteopenia (low bone density)

Use with care, and tell your doctor, if

• if you have prostate trouble or difficulty passing urine
• if you are 65 years of age or older, you are taking other medicines which can cause a drop in blood pressure or if you have any conditions that are risks for the drop of blood pressure
• if you have low blood volume (hypovolaemia)
• if you have low blood pressure
• if you have any liver sickness, kidney or heart problems
• if you have diabetes. If you are taking insulin, your doctor may need to adjust your insulin dosage
• if you feel dizzy or feel dehydrated. This can happen if you have lost a lot of water through being sick, having diarrhoea or passing water very often. It can also happen if you are having trouble drinking or eating, or are sweating excessively, such as during strenuous exercise
• if you are on a sodium restricted diet before taking this medicine
• if you have gout (severe joint pain)
• if you take curare medication
• if you are taking risperidone treatment
• if you are taking or have been on antibiotics
• if you develop severe pain in your stomach with nausea and vomiting (could be signs of inflammation of your pancreas)
• if you develop hearing problems
• if you are going to have a glucose test
• if you have a condition called lupus erythematosus. It may be necessary to increase the potassium in your diet or take a potassium supplement. Food that is rich in potassium include lean meat, potatoes, bananas, tomatoes, cauliflower, spinach and dried fruit. Do not change your diet on your own, ask your doctor for advice
• This is more important if you are already on a special diet (as for diabetes), or if you are taking a potassium supplement. If you are taking heart medication, inform your doctor before taking this medication, as the loss of potassium could be of concern. You may experience gout attacks while on FUROSEMIDE 40 UNIMED treatment. Diabetes mellitus (increase in blood sugar) may be worsened by FUROSEMIDE 40 UNIMED treatment and latent diabetes may become manifest. It is recommended to undergo regular monitoring of blood levels for sodium, potassium, kidney function (creatinine levels) while taking FUROSEMIDE 40 UNIMED Children and adolescents Safety and efficacy of FUROSEMIDE 40 UNIMED in children has not been established

Pregnancy and breastfeeding

• FUROSEMIDE 40 UNIMED should not be used during pregnancy and breast-feeding
• If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, please consult your doctor, pharmacist or other health care provider for advice before taking this medicine

Interactions and medicines to check

The approved leaflet names these interactions.

• Medicines such as ramipril, enalapril, perindopril (called angiotensin-converting enzyme [ACE] inhibitors) or losartan, candesartan, irbesartan (called angiotensin II receptor antagonists), used to treat high blood pressure. Your doctor may need to change the dose of your medicine or ask you to stop taking it
• Medicines for high blood pressure or heart problems such as alpha or beta blockers (methyl dopa, prazosin, carvedilol, sotalol). Your doctor may need to change the dose of these medicines
• Medicines for psychosis such as amisulpride or sertindole (increases the risk of having a heart rhythm dysfunction), chlorpromazine (may drop blood pressure too much), pimozide (may cause drop in potassium levels)
• Medicines for heart rhythm problems such as amiodarone, disopyramide, flecainide
• Medicines for treating depression such as reboxetine (may cause drop in potassium levels), amitriptyline, imipramine, selegiline or tranylcypromine (may drop the blood pressure)
• Nonsteroidal anti-inflammatory drugs (NSAIDs) (used to treat pain, fever and inflammation), such as aspirin, ibuprofen, ketoprofen or indomethacin
• Antibiotics (used to treat bacterial infections), especially those that affect the kidneys or ears such as gentamicin, amikacin, neomycin, netilmicin, tobramycin, vancomycin, tetracyclines, colistin or high doses of cephalosporins
• Phenytoin or carbamazepine (used to treat epilepsy and seizures [fits]). Epilepsy medication reduces the effect of FUROSEMIDE 40 UNIMED
• Amphotericin B (antifungal medicine)
• Nelfinavir, ritonavir or saquinavir (antiviral medicines)
• Atomoxetine (medicine for treatment of attention deficit hyperactivity disorder (ADHD))
• Phenobarbital and other barbiturates (medicines for epilepsy or to assist with sleeping)
• Digoxin (used to treat heart problems). Your doctor may need to change the dose of digoxin
• Ciclosporin or tacrolimus (used to prevent the rejection of organs after a transplant)
• Corticosteroids, such as prednisone (used to treat inflammation)
• Other water tablets (diuretics) such as hydrochlorothiazide. Your doctor may need to change your dose of FUROSEMIDE 40 UNIMED
• Lithium (used as a mood stabiliser or to treat mental illness). To help stop the side effects your doctor may need to change the dose of your lithium and check the amount of lithium in your blood
• Sucralfate (used to treat duodenal ulcers). FUROSEMIDE 40 UNIMED and sucralfate should not be used within 2 hours of each other
• Salbutamol or salmeterol (medicines for asthma)
• Theophylline (used for wheezing, cough or difficulty in breathing)
• Levothyroxine (used to treat an underactive thyroid gland)
• Medicines used for constipation (laxatives) if used for a long time, such as bisacodyl or senna
• Carbenoxolone (used to treat ulcers) or liquorice, often used in cough medicines if taken in large amounts
• Warfarin (medicine for blood clotting) and clofibrate (medicine for treating cholesterol levels)
• Probenecid (used to treat gout), as it may reduce the effect of FUROSEMIDE 40 UNIMED
• Methotrexate (used to treat autoimmune diseases, rheumatoid arthritis and some cancers)
• Risperidone (used to treat schizophrenia and bipolar disease)
• Aliskiren (used to treat high blood pressure)
• Astemizole (an antihistamine) or halofantrine (medicine for malaria), as these can affect the heart rhythm
• Medicines used for relaxing your muscles during surgery
• Medicines used as injections for x-ray examinations
• Nicotine in tobacco reduces the effect of furosemide
• Medicines for diabetes. These may not work as well when you are taking FUROSEMIDE 40 UNIMED
• Allopurinol (treatment of gout and kidney stones)
• Medicines that have a poisonous effect on the kidneys
• Do not take FUROSEMIDE 40 UNIMED if you are taking: chloral hydrate (sleep inducing medicine), ethacrynic acid (medicine for treating high blood pressure, swelling or fluid retention) or cisplatin (anti-cancer medication)
• Corticotrophin, which enhances the potassium loss due to FUROSEMIDE 40 UNIMED

What to do if you experience side effects

If you think you are having a side effect, the response depends on how severe it is. Use the warning signs above first — if any of those apply, treat it as urgent.

If the symptom is severe or frightening

Get medical help immediately. Call 10177 for an ambulance, or 112 from a mobile phone, or go to the nearest emergency department. Take the product and its packaging with you if you can.

If the symptom is mild but bothering you

• Write down what the symptom is, when it started, and how it relates to when you take the product
• Check the leaflet that came with the product to see whether the symptom is listed
• Speak to your pharmacist — for many questions this is the fastest route to a useful answer
• Contact the prescriber if the symptom is affecting your daily life or is not settling

You can also report a suspected side effect in South Africa. Reporting does not replace getting medical advice, and you do not need to be certain the product was the cause.

When to seek urgent medical help

Some symptoms need medical attention straight away rather than an appointment in a few days. Do not wait to see whether they settle.

Get same-day medical advice if you have

• A high fever, or a rash together with feeling generally unwell
• Yellowing of the eyes or skin, or unusually dark urine
• Unusual bruising or bleeding that you cannot explain
• Severe or persistent vomiting or diarrhoea, especially if you cannot keep fluids down
• A sudden change in mood, or thoughts of harming yourself
• Any symptom that is rapidly getting worse

How to report a suspected side effect in South Africa

South Africa has an official system for reporting suspected side effects, run by the South African Health Products Regulatory Authority (SAHPRA). Reports from the public and from healthcare professionals are how safety signals get detected after a product is already in use.

Who can report

Anyone can report — you do not have to be a healthcare professional, and you do not need to prove that the product caused the problem. A suspicion is enough. Patients, caregivers and family members can all submit a report.

What to have ready

• The name of the product, its strength and form, and the batch number if you have it
• Why it was being used, and when it was started and stopped
• What the suspected reaction was, when it began, and how long it lasted
• Any other medicines, supplements or remedies being used at the same time
• Basic details about the person affected — age and sex are usually enough

How to report

SAHPRA accepts adverse reaction reports through its e-Services reporting system and through the Med Safety mobile app. Healthcare professionals can also report through the same routes. Current forms and access points are published on the SAHPRA site.

• SAHPRA Health Products Vigilance — the main vigilance and reporting hub
• SAHPRA e-Services — current adverse reaction reporting access

For a fuller walkthrough see how to report an adverse drug reaction.

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