Water tablets help the body get rid of extra fluid and salt, easing swelling, breathlessness and high blood pressure. They work well, but timing your dose and knowing the warning signs of side effects makes a big difference to daily life.
Imagine taking your furosemide at breakfast before a long bus journey into town, then spending the trip desperately looking for a toilet. A small change in timing could have made the day much easier.
How diuretics work
Diuretics act on the kidneys to increase the amount of salt and water passed in the urine. This reduces fluid in the body and blood vessels, which lowers blood pressure and relieves fluid build-up in the lungs, legs and tummy.
Main types of diuretic
- Loop diuretics (furosemide, bumetanide, torasemide): strong and fast-acting, mainly used for fluid build-up in heart failure, kidney and liver disease
- Thiazide and thiazide-like diuretics (bendroflumethiazide, indapamide, chlortalidone, hydrochlorothiazide): milder, mainly used for high blood pressure
- Potassium-sparing diuretics (spironolactone, eplerenone, amiloride): used in heart failure, liver disease and some types of high blood pressure; they can raise potassium
When to take them
Most people take diuretics in the morning, so they are not up at night passing urine. If you take two doses a day, the second is usually taken around early afternoon.,On days when you need to go out, you may be able to adjust the timing slightly, for example taking a dose after you get home. Ask your healthcare provider or pharmacist whether this is safe for you.
Common side effects
- Needing to pass urine more often, especially in the first few hours after a dose
- Dehydration and thirst
- Dizziness, especially when standing up
- Low potassium or sodium levels (loop and thiazide diuretics)
- High potassium (potassium-sparing diuretics)
- Gout flares, particularly with thiazides and loop diuretics
- Raised blood sugar in some people
- Breast tenderness or enlargement with spironolactone
Signs of dehydration or salt imbalance
- Feeling very thirsty or having a dry mouth
- Dark urine or passing very little urine
- Dizziness, fainting or falls
- Muscle cramps or weakness
- Confusion, especially in older adults
- Seek medical advice promptly if you notice these
Blood tests
Diuretics can change sodium, potassium and kidney function, so regular blood tests are important. They are usually done a few weeks after starting or changing the dose and then at least once a year, more often in older adults and people with kidney or heart problems.
Daily weight in heart failure
If you take diuretics for heart failure, weighing yourself every morning, after using the toilet and before breakfast, is one of the best ways to spot fluid build-up early. A gain of about 2 kg over three days, or increasing breathlessness or ankle swelling, can mean you need your diuretic dose adjusted.,Many heart failure teams give patients a personal plan for adjusting their diuretic dose. Only do this if your team has agreed it with you.
Sick day rules
If you have vomiting, diarrhoea or a fever and cannot drink normally, diuretics can make dehydration and kidney injury more likely. Your healthcare provider may advise pausing them temporarily until you are eating and drinking normally again. Follow your personal advice and seek help if you are unsure.
Hot weather and travel
- Drink regularly, following any fluid advice you have been given
- Watch for dizziness and dark urine
- Stand up slowly
- Plan toilet stops when travelling
- Take a list of your medicines and a copy of your latest blood test results when travelling
Frequently asked questions
Can I drink less to avoid going to the toilet?
Do not restrict fluids unless your healthcare provider has told you to, as this can cause dehydration.
Do diuretics help weight loss?
They only remove water, not fat, and should never be used for weight loss.
Can I take them with ibuprofen?
Anti-inflammatory painkillers can reduce diuretic effects and strain the kidneys. Check with your pharmacist first.
But I keep getting dizzy. Should I stop?
Do not stop on your own, especially if you have heart failure. Tell your healthcare provider; your dose may need adjusting.
Your next step: If you take a diuretic, ask when your next blood test is due and write it in your diary.
Related: Heart failure: daily weight and fluid · Urea and electrolytes test
Sources: British National Formulary (BNF), National Institute for Health and Care Excellence, British Heart Foundation, American Heart Association.
Leave a Reply