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Detailed medicine guidance

Side effects of bendroflumethiazide

NHS medicines information on side effects of bendroflumethiazide and what you can do to cope.

About this information

This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.

Common side effects of bendroflumethiazide

There are things you can do to help cope with these side effects of bendroflumethiazide:

Needing to pee more often

Try to make sure you can get to a toilet easily. Also, take it in the morning or you may need to get up in the night to use the toilet.

Speak to a pharmacist or doctor if you're finding it hard to get to the toilet in time.

Feeling thirsty, with a dry mouth

It's important not to get dehydrated, but how much you can drink will depend on why you're taking bendroflumethiazide. Check with your doctor how much water you can drink while you're taking this medicine.

Feeling or being sick (nausea or vomiting)

Stick to simple meals and do not eat rich or spicy food. If you're being sick, try frequent small sips of water to avoid dehydration. Speak to your doctor if your symptoms continue.

If you take the combined contraceptive pill or progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.

Diarrhoea

Drink plenty of water or other fluids. Speak to a pharmacist if you are peeing less than usual or have dark yellow and strong-smelling pee, as you could be at risk of dehydration.

Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.

If you take the combined contraceptive pill or progestogen-only pill and have severe, watery diarrhoea or any diarrhoea that lasts more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.

Loss of appetite

Eat when you would usually expect to be hungry. If it helps, eat smaller meals but more often than usual. Snack when you're hungry and choose nutritious snacks that are high in calories and protein, such as dried fruit and nuts.

Constipation

Get more fibre into your diet by eating fresh fruit, vegetables and cereals, and drink plenty of water. Try to exercise more regularly, for example, by going for a daily walk or run. If this does not help, talk to your pharmacist or doctor.

Severe joint pain

If you get sudden severe pain in any joint, such as your big toe, wrists, elbows or knees and the skin over the joint is hot, swollen and red, this could be a sign of gout. The redness may be less noticeable on brown or black skin.

Speak to your doctor if you have these symptoms.

Feeling dizzy and faint

These could be signs of low blood pressure (hypotension).

If you feel dizzy or faint, stop what you're doing. Try sitting or lying down until you feel better, and then get up slowly. A drink of water may also help. Do not drive, ride a bike or operate machinery if you are affected.

Speak to your doctor if this keeps happening.

Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.

View the original NHS website page ↗. Refreshed 19 August 2026.

Licensed under the Open Government Licence v3.0 ↗. MyPHU is independent and is not endorsed by the NHS.

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