Indapamide: blood pressure tablet, side effects and monitoring

Indapamide is used to control high blood pressure, which usually causes no symptoms but quietly raises the risk of heart attack and stroke over years. It is a diuretic, so it works by making you pass more urine, lowering the volume of fluid in the blood vessels.

Treatment is often long term. People generally take it alongside lifestyle measures and sometimes with other blood pressure tablets, with the prescriber reviewing the combination from time to time.

Indapamide comes as a tablet that you swallow whole with some water, usually once a day and in the morning. Morning dosing means the extra urine is mostly passed in daytime. The NHS says you can eat as normal while taking it.

Exact doses are set by your prescriber and are on the label. If you miss one, take it when you remember unless the next dose is nearly due, then skip it; never double up. A single extra tablet is unlikely to cause problems, but get medical advice from a pharmacist or NHS 111.

Most adults can take it. The NHS lists the following as reasons for caution: a past allergy to indapamide or a similar medicine, diabetes, kidney or liver disease, a history of gout, heart rhythm problems, Addison's disease, and blood tests showing low potassium or salt or high calcium.

Because several of these relate to blood chemistry, a baseline blood test is often part of getting started. Tell the prescriber about every condition you have and every medicine you use.

Common effects include a bumpy red rash, which can be harder to see on darker skin, headaches, nausea, and low blood pressure that makes you dizzy when standing. At first you may pass more urine, and that normally settles within a few weeks.

Serious but uncommon problems are anaphylaxis, a low potassium level and acute pancreatitis. Low potassium can bring tiredness, constipation, muscle pain or cramps and an abnormal heart rhythm; pancreatitis shows as severe abdominal pain. Call NHS 111 if you suspect a serious effect, and use 999 for anaphylaxis, signalled by a swollen throat or tongue, an itchy raised rash and difficulty breathing.

Medicines the NHS lists as able to interact include anti-inflammatory painkillers such as ibuprofen, calcium supplements, lithium, tricyclic antidepressants such as amitriptyline and nortriptyline, allopurinol, heart rhythm medicines and other blood pressure treatments. A pharmacist can check anything new.

Avoid alcohol because it can raise the risk of low blood pressure. Indapamide is not usually recommended in pregnancy, and it is not usually used while breastfeeding because small amounts may pass into breast milk, so talk to your doctor if either applies.

The core of monitoring is regular blood tests to check that indapamide is not affecting your potassium levels. Your blood pressure will also be measured at reviews to see whether the dose is working.

Do not stop taking it because you feel well; high blood pressure often has no symptoms, and the benefit comes from steady control. Ask your prescriber if you want to discuss side effects or alternatives.