Common questions about bendroflumethiazide

Bendroflumethiazide is a type of medicine called a thiazide diuretic.

A thiazide diuretic helps your body get rid of extra fluid and water that you pee out.

This means you have less fluid in your tissues, which helps get rid of swelling and a build-up of fluid in your body (oedema). You will also have less fluid in your blood vessels, which helps reduce your blood pressure.

Bendroflumethiazide takes around 2 hours to start working.

When you first start taking bendroflumethiazide it may take 3 or 4 days for your blood pressure to come down to target levels.

After taking a dose of bendroflumethiazide, the effects will usually last about 12 to 24 hours.

You need to keep taking bendroflumethiazide regularly at the dose recommended by your doctor for it to continue to work.

Bendroflumethiazide is safe to take for a long time if it's needed. Check with your doctor how long you will need to take it for. See your doctor or nurse regularly to check your blood pressure and for blood tests.

This is to make sure your kidneys are working well and the salts (electrolytes) in your blood are properly balanced.

How often you'll need these tests will depend on the reason you're taking bendroflumethiazide, if your dose has changed recently or if you have any other health problems.

If you stop taking bendroflumethiazide, your blood pressure is likely to go back up. Or, if you're taking it for a build-up of fluid (oedema), you may find extra fluid starts to become a problem again.

The levels of salts (electrolytes) in your blood might also change when you stop taking bendroflumethiazide. Your doctor may suggest having a blood test after a week or 2 to check this.

Unless you've been advised by a doctor or nurse to limit how much fluid you drink, it's usually best to drink normally while you're taking bendroflumethiazide. A good rule is to drink enough so that you're not thirsty for long periods.

Speak to a doctor if you're feeling unwell and not able to drink properly.

Steadily increase the amount you drink when you're exercising and during hot weather. If your pee's pale yellow or clear, then you're probably drinking enough fluid.

There are other diuretics, including other thiazide diuretics, that can help treat high blood pressure or a build-up of fluid.

Other thiazide diuretics include indapamide, chlortalidone, hydrochlorothiazide and metolazone. Other types of diuretics include furosemide, bumetanide, amiloride and spironolactone.

There are also lots of other types of medicines to lower your blood pressure. They work in a different way to diuretics and include:

• ACE inhibitors like ramipril and lisinopril
• angiotensin receptor blockers like losartan and candesartan
• beta blockers like atenolol and bisoprolol
• calcium channel blockers like nifedipine and amlodipine

If you have high blood pressure, you'll often need to take more than one medicine to get the best effect.

If you cannot take bendroflumethiazide because of side effects, you may be able to switch to another medicine. Your doctor will advise which high blood pressure medicines are best for you depending on your age, ethnicity and health.

Bendroflumethiazide does not make asthma worse. However, some medicines used to treat asthma can cause low levels of potassium in your blood, and this is also a side effect of bendroflumethiazide.

Speak to your doctor if you have asthma and have questions about whether bendroflumethiazide is safe for you.

If you get diarrhoea or you've been sick (vomiting), from a stomach bug or other illness, or you're not able to eat or drink properly, tell your doctor or speak to a pharmacist.

You may need to stop taking bendroflumethiazide for a short time. This is because taking bendroflumethiazide can increase the risk of acute kidney injury, which is damage to your kidneys that can happen suddenly if you are not able to eat or drink properly or if you lose too much fluid due to diarrhoea or vomiting.

Make sure you tell the doctor or nurses that you're taking bendroflumethiazide if you're going to have surgery, especially if you're having a general anaesthetic.

Bendroflumethiazide can reduce your blood pressure when it's taken with a general anaesthetic.

The doctor may advise you to stop taking bendroflumethiazide 24 hours or more before surgery.

Bendroflumethiazide will not affect any type of contraception including emergency contraception.

However, some types of hormonal contraception, like the combined pill and contraceptive patch or vaginal ring, are not usually recommended if you have high blood pressure. Talk to your doctor if you're taking a hormonal contraceptive.

If bendroflumethiazide makes you vomit or have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.

Find out more:

• What to do if you're sick or have diarrhoea when taking the combined pill
• What to do if you're sick or have diarrhoea when taking the progestogen-only pill

Bendroflumethiazide can make you feel dizzy. If this happens to you, do not drive a car, ride a bike, or use tools or machinery until you feel better.

Drinking alcohol with bendroflumethiazide can lower your blood pressure or cause dehydration and make you feel dizzy or lightheaded.

During the first few days of taking bendroflumethiazide, or after increasing your dose, wait to see how the medicine affects you before you drink any alcohol.

If you feel OK, you can drink. Follow the national guidelines of no more than 14 units a week for men and women.

If you have high blood pressure, it's best not to drink alcohol in large amounts regularly as this can raise your blood pressure further.

Try to avoid very strict low salt or low sodium diets while you're taking bendroflumethiazide. This is because it can cause low levels of salts (or electrolytes) in your body.

Drinking lots of tea, coffee, hot chocolate, cola, energy drinks and other drinks with caffeine can make you more thirsty and need to pee more. Small amounts should be fine, but make sure you drink plenty of other fluids, such as water or squash, or have decaffeinated drinks instead.

You can improve your general health and the health of your heart by making some key lifestyle changes. These will also help if you have high blood pressure.

• Try to lose weight if you need to.
• Quit smoking – smoking increases your heart rate and blood pressure. Quitting smoking brings down your blood pressure and reduces your risk of heart disease and stroke. Try to avoid secondhand smoke too.
• Limit how much alcohol you drink – too many alcohol units can raise your blood pressure over time. If you have high blood pressure, avoid drinking large amounts of alcohol regularly.
• Exercise – regular exercise lowers blood pressure by keeping your heart and blood vessels in good condition. It does not need to be too energetic, walking every day can help.
• Eat well – aim to eat a diet that includes plenty of fruit and vegetables, wholegrains, fat-free or low-fat dairy products, and lean proteins. It's a good idea to reduce the amount of salt in your diet too. Eating too much salt is the biggest cause of high blood pressure. The more salt you eat, the higher your blood pressure will be. Aim for no more than 6g of salt a day, but avoid very strict low salt or low sodium diets while you're taking bendroflumethiazide.
• Manage stress – when you're anxious or upset, your heart beats faster, you breathe more heavily and your blood pressure often goes up. Find ways to reduce stress in your life. Try napping or putting your feet up when possible. Spend time with friends and family to be social and help avoid stress.
• Vaccinations – if you have a serious long-term health condition such as being very overweight, coronary heart disease, heart failure, diabetes, liver disease or chronic kidney disease (CKD), it's recommended that you have the flu vaccine every year, and the pneumococcal vaccine and COVID-19 vaccine as recommended by your GP. Ask your doctor about these vaccinations. You can have them free on the NHS if you are eligible.

If you have a build-up of fluid (oedema), you can also try:

• resting with your legs raised on a chair or pillows when you can
• taking gentle exercise, such as walking
• avoiding standing for long periods of time