Angiotensin receptor blockers (ARBs) and kidney impairment: monitoring and sick-day care

The NHS describes losartan as a type of medicine called an angiotensin receptor blocker. It is mainly used for high blood pressure and also helps treat heart failure and kidney disease caused by type 2 diabetes. Other ARBs include candesartan, irbesartan and valsartan.

The NHS says your doctor arranges blood tests to check how losartan is affecting your kidneys, which tells you that kidney function is something these medicines can influence and that it is watched. For some people with kidney disease the medicine is part of the treatment, and for others the kidneys simply need to be monitored.

The NHS losartan page says your doctor will arrange for you to have blood tests and blood pressure checks while you take it, to check how it is affecting your blood pressure and your kidneys. How often they are repeated is set by your clinician.

When kidney function is already reduced, the checks matter even more. NHS pages on chronic kidney disease note that CKD is a long-term condition where the kidneys do not work as well as they should, that there are usually no symptoms in the early stages, and that it may only be found when a blood or urine test is done for another reason. That is why attending monitoring appointments is a real safeguard, not a formality.

The NHS losartan page lists categories to tell your doctor about. The BNF adds detail on how some of them increase risks for the kidneys or potassium.

• ACE inhibitors such as ramipril or lisinopril: the BNF says ramipril increases the risk of renal impairment when given with losartan, with manufacturer advice to avoid or monitor.

• Potassium-sparing diuretics such as spironolactone, potassium supplements and salt substitutes: the NHS lists these, and the BNF notes risk of hyperkalaemia.

• NSAIDs including ibuprofen and diclofenac: the BNF says they can increase the risk of hyperkalaemia with losartan, and the NHS lists some NSAIDs among medicines that may not mix well.

• Lithium: the BNF says losartan potentially increases the concentration of lithium, with advice to avoid or monitor.

• Aliskiren: the BNF says it increases the risk of renal impairment with losartan.

The NHS says that if you get ill with vomiting, diarrhoea or a high temperature there is a risk of dehydration, and to talk to a pharmacist or doctor for advice or follow the advice already given. The advice may involve temporarily pausing the medicine until you are eating and drinking normally, which the NHS says for ramipril, an ACE inhibitor with a similar action. Ask your own prescriber what applies to you, and do not stop on your own initiative without checking.

The NHS acute kidney injury page lists dehydration, infections and medicines such as ACE inhibitors, NSAIDs and diuretics among causes of AKI. It advises people at higher risk to stay hydrated, speak to a doctor before taking new medicines or supplements, and know the symptoms to watch for.

The NHS losartan page lists serious side effects including a fast or irregular heartbeat, problems with the liver, and allergic reaction. For the kidneys, the NHS AKI page lists peeing much less than usual, feeling very thirsty, feeling or being sick, swollen feet or legs, tiredness, dizziness, confusion or breathlessness, and advises asking for an urgent GP appointment or calling NHS 111.

Call 999 for swelling of the throat or tongue, difficulty breathing or collapse. For palpitations that are severe or accompanied by chest pain, also call 999.

Many people with kidney disease live well for a long time, as the NHS says. Practical habits help: keep blood test appointments, bring a medicines list to every visit, check with a pharmacist before buying painkillers or supplements, and avoid grapefruit juice with losartan as the NHS advises.

Treatment pathways differ between NHS and private care mainly in who sees you, not in which references are used. Whichever route you use, make sure the kidney team, GP and any other prescriber share the same list.