Bendroflumethiazide

What is Bendroflumethiazide?

Bendroflumethiazide is a medicine used to treat high blood pressure (hypertension) and swelling caused by a build-up of fluid in the body (oedema).

What does Bendroflumethiazide do?

Bendroflumethiazide gets rid of fluid and salt from the body by making you urinate more. This helps to reduce blood pressure.

How does Bendroflumethiazide work?

Bendroflumethiazide is a diuretic that works by giving you the urge to pass urine, increasing the flow of salt and fluids from the body. It also relaxes the blood vessels, helping blood flow through your body.

How long does Bendroflumethiazide take to work?

Bendroflumethiazide starts working within hours. People usually need to pee about 2 hours after taking a dose of Bendroflumethiazide, and then again a few hours later. One dose of Bendroflumethiazide is effective for 12-24 hours.

Active ingredients

Bendroflumethiazide tablets contain either 2.5mg or 5mg of the active ingredient Bendroflumethiazide.

Inactive ingredients

As well as Bendroflumethiazide, your medication also contains inactive ingredients. These are lactose, magnesium stearate, maize starch, pregelatinised maize starch, stearic acid and water.

Please Note: Inactive ingredients may vary between different brands of generic Bendroflumethiazide.

How to take Bendroflumethiazide

Bendroflumethiazide is available in tablet or liquid form. Tablets should be swallowed whole with a glass of water. You can take them with or without food.   Liquid Bendroflumethiazide should always be measured out using the spoon or syringe included in the packaging. Shake the bottle well before taking it.  

Bendroflumethiazide dosage

Your GP will advise you on dosage, but for treating high blood pressure, the usual dosage is one 2.5mg tablet daily. Tablets are available in 2.5mg and 5mg dosages, and for oedema you may be prescribed up to 10mg of Bendroflumethiazide per day.   If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the forgotten dose and take the next one on schedule.   If you overdose on Bendroflumethiazide, seek medical attention.  

Bendroflumethiazide side effects

As with all medications, some people may experience side effects when taking Bendroflumethiazide. These are usually mild, and can include:

• Dry mouth and feelings of thirst, because your body is expelling more fluid than usual.
• Nausea and / or vomiting
• Stomach pain
• Joint pain
• Diarrhoea or constipation
• Feelings of dizziness or faintness, which could indicate low blood pressure
• Loss of appetite
• Weight loss, bladder or skin infections, thrush, blurred vision, tiredness and blurred vision. Together, these may indicate a problem with your blood sugar.

  Most side effects will subside as your body adjusts to the medicine. If you are experiencing prolonged unpleasant side effects, see your GP. They may suggest reducing your dose, or trying an alternative medication that may suit you better.   Serious side effects of Bendroflumethiazide are rare. If you experience any of the following symptoms, seek medical help immediately.

• Blood problems, such as unexplained bruising or bleeding
• Severe stomach pain, especially if it comes on suddenly.
• Signs of jaundice, including yellowed skin or eyes, dark-coloured urine and pale faeces.
• Symptoms of dehydration, such as dark-coloured urine, extreme thirst, feeling faint and urinating less than 4 times a day.
• Symptoms of anaphylaxis (a severe allergic reaction), such as a skin rash, wheezing, tightness in the chest or throat or difficulty breathing,  or swollen lips, face, tongue or throat.

Contraindications

Bendroflumethiazide is not suitable for everyone. It should not be taken if you have:

• Kidney problems
• Liver problems
• Gout
• Addison’s disease
• Hypercalcaemia (a high level of calcium in the blood)
• Hypokalaemia (low levels of potassium in the blood)
• Hyponatraemia (low levels of sodium in the blood)
• Allergies to other thiazide diuretics
• Allergies to any of the ingredients.

Do not take Bendroflumethiazide if you are pregnant or breastfeeding.  

Drug interactions

Other drugs or medicines may interfere with the way that Bendroflumethiazide works, or cause harmful symptoms. Always talk to your doctor if you are taking other prescription or non-prescription drugs, so that they can decide which treatment is safest.   In particular, be aware of the following known drug interactions with Bendroflumethiazide:

• NSAIDs (non-steroidal anti-inflammatory drugs) including Ibuprofen, Naproxen and Aspirin.
• Heart medicines including Amiodarone, Digoxin, Disopyramide, Flecainide and Sotalol
• Antiemetic medicines, including Domperidone, Metoclopramide and Prochlorperazine
• Antidepressant drugs, including Amitriptyline, Citalopram and Venlafaxine
• Mental health treatments, including Chlorpromazine, Pimozide, Trifluoperazine and Lithium
• Asthma treatments, including Formoterol, Salbutamol and Salmeterol
• Allopurinol (used to treat gout)
• Ciclosporin (a treatment for psoriasis and rheumatoid arthritis)
• Medicines used to treat diabetes, including insulin
• Carbamazepine (an epilepsy treatment)
• Corticosteroids and other types of diuretic
• Medicines affecting the levels of salt in your blood, including potassium, sodium, calcium and magnesium
• Calcium and Vitamin D supplements, including Calcitriol and Alfacalcidol.

This is not an exhaustive list, so always seek medical advice if you are taking other medicines or herbal remedies.  

How to cope with Bendroflumethiazide side effects

Most side effects of Bendroflumethiazide are mild and can be managed effectively.   You may feel more thirsty than usual. Check with your doctor how much water you should be drinking to prevent dehydration, because depending on your condition, drinking too much liquid could be harmful.   Some people experience nausea when they take Bendroflumethiazide, or they may vomit. If this happens to you, avoid rich or spicy foods, and try eating little and often. Small sips of water can also help. See your doctor if symptoms continue for more than a week.   You might have some stomach pain. If this happens, relaxing with a hot water bottle can help to mitigate the pain. Eat little and often, and see your doctor if the pain continues. Any sudden, severe pain should be checked by a doctor immediately.   If you experience diarrhoea, you may be at risk of dehydration, so keep up your fluid intake and check with your doctor how much water you should drink. Medications to treat diarrhoea may interact with Bendroflumethiazide, so do not take anything without speaking to a doctor or pharmacist.   Constipation can be improved by eating plenty of fruit, vegetables and fibre-rich foods, and drinking water. Regular exercise can also help, and this doesn’t have to be strenuous – a daily walk can be enough to help your digestive system.   Some people lose their appetite when they start taking Bendroflumethiazide. If this happens to you, it’s important to make sure you are receiving all the nutrients you need. Keep your mealtimes the same, but eat less if you feel like it. Make sure the meals you do eat are nutritious, and snack when you feel hungry.   Because Bendroflumethiazide works to reduce your blood pressure, you may experience symptoms like dizziness and faintness, which are signs of low blood pressure. If you feel faint or dizzy, stop what you are doing, and do not drive or operate machinery. Seek medical advice if symptoms continue, as you may need to reduce your dose.   There are some side effects that cannot be managed without medical help. Joint pain can be a symptom of gout, while weight loss, skin infections, bladder infections, thrush, tiredness, blurred vision and thirst together could indicate high blood sugar. If you experience these, or any other painful or worrying symptoms, seek medical advice.  

Drinking and Bendroflumethiazide

Because alcohol can affect your blood pressure, it is advisable to avoid drinking for a few days when you first start taking Bendroflumethiazide. After this, you can drink in moderation (following the national guidelines on alcohol units). If you feel dizzy or dehydrated, it may be best to avoid drinking while you are taking Bendroflumethiazide.   If you have very high blood pressure, you should avoid alcohol because it can raise your blood pressure further.  

Driving and Bendroflumethiazide

Dizziness can be a side effect of Bendroflumethiazide, so it’s sensible to wait and see how you react to the medicine before driving or operating heavy machinery. If you feel dizzy, do not drive until you feel better.

Pregnancy and Bendroflumethiazide

Bendroflumethiazide is not recommended for use by patients who are pregnant. That’s because the drug can reduce blood flow, cutting down the volume of blood that reaches the baby through the placenta, posing a risk to the baby’s health. Pregnant women with high blood pressure are normally prescribed alternative medicines.   Breastfeeding women are advised not to take Bendroflumethiazide because it can be passed on to the baby in the mother’s milk. Bendroflumethiazide can also reduce the amount of milk produced.  

Will Bendroflumethiazide affect my contraception?

No, Bendroflumethiazide does not reduce the effectiveness of any form of contraception. If you have high blood pressure, however, some forms of hormonal contraception such as the pill and the patch may not be suitable for you. Talk to your GP if you have any concerns.

Will Bendroflumethiazide affect my fertility?

There are no studies linking Bendroflumethiazide with a fall in fertility, although having high blood pressure can make both women and men less fertile. In some cases, however, Bendroflumethiazide can affect men’s ability to get an erection. If this happens to you, talk to your GP. They may stop treatment for a few weeks to see if Bendroflumethiazide is the cause.

Bendroflumethiazide vs other diuretics

Bendroflumethiazide is one of a class of thiazide diuretics, which are usually prescribed to treat hypertension. Other thiazide diuretics include Chlortalidone, Cyclopenthiazide, Indapamide, Metolazone and Xipamide. These are not suitable for all patients: in particular, people with conditions including gout, Addison’s disease, kidney disease or liver disease should not be prescribed thiazide diuretics.   Two other classes of diuretic are also available: loop diuretics and potassium-sparing diuretics.   Loop diuretics include Bumetanide, Furosemide and Torasemide. These may be more suitable than thiazide diuretics for patients with impaired kidney function.   If potassium levels are a concern, you may be prescribed a potassium-sparing diuretic such as Eplerenone, Spironolactone, Triamterene or Amiloride instead of Bendroflumethiazide. This type of diuretic medicine will not cause your potassium levels to drop.  

Alternatives to Bendroflumethiazide

Depending on why you are taking Bendroflumethiazide, there may be several alternative treatments available.   For hypertension, lifestyle changes such as cutting down salt in your diet may help to reduce your blood pressure and even avoid medication altogether. Other blood pressure medicines include:

• ACE inhibitors such as Enalapril, Lisinopril, Perindopril and Ramipril, which relax the blood vessels.
• Angiotensin-2 receptor blockers (ARBs) such as Candesartan, Irbesartan, Losartan, Valsartan and Olmesartan, which also help to relax the blood vessels and promote blood flow.
• Calcium channel blockers such as Amlodipine, Felodipine and Nifedipine, which widen the blood vessels.
• Beta blockers, such as Atenolol and Bisoprolol, which slow down your heartbeat.
• Other thiazide diuretics, such as Chlortalidone, Cyclopenthiazide, Indapamide, Metolazone and Xipamide.
• Loop diuretics and potassium-sparing diuretics may also be prescribed as an alternative to Bendroflumethiazide.

  For oedema, lifestyle changes such as staying active, reducing salt intake and elevating the affected part of the body can all help reduce your symptoms. Alternative types of diuretic can also be prescribed.  

Can Bendroflumethiazide help asthma?

Bendroflumethiazide is a blood pressure treatment and is not prescribed to treat asthma. If you do have asthma, however, it is important to check with your GP before taking Bendroflumethiazide. That’s because, like some asthma treatments, Bendroflumethiazide can reduce the levels of potassium in your blood. Your GP will need to ensure that it is safe for you to take these medicines at the same time.

What is a diuretic?

A diuretic (sometimes called a water tablet) is a substance or medication that makes you urinate more than usual. Bendroflumethiazide is what’s known as a thiazide diuretic, which is most often used to treat high blood pressure.

Can I take Bendroflumethiazide before surgery?

Because Bendroflumethiazide acts to reduce your blood pressure, it could cause dangerously low blood pressure when combined with a general anaesthetic. Talk to your surgeon before the procedure takes place. They may advise you to stop taking Bendroflumethiazide 24 hours before your surgery is scheduled.

Is long term use of Bendroflumethiazide safe?

Yes, it is usually safe to take Bendroflumethiazide for an extended period of months or years. However, if you are taking it long-term you should have periodic check-ups with your GP or nurse to make sure the Bendroflumethiazide isn’t causing a chemical imbalance in your blood, that your kidney function is normal, and that it continues to be the best treatment for your condition.

Sources

• Patient Information Leaflet
• NHS > Bendroflumethiazide