Blood pressure medicines and your kidneys

If your doctor has started you on a tablet for blood pressure, such as an ACE inhibitor or an ARB (names like ramipril, enalapril, telmisartan or losartan), it is natural to wonder what it is doing to your kidneys. For most people the answer is reassuring: these are among the most kidney-protective medicines we have.

High blood pressure and the kidneys are tightly linked. Raised pressure slowly damages the tiny filters inside the kidneys, and damaged kidneys in turn push the pressure higher, a cycle that quietly drives a great deal of kidney disease. Bringing the pressure down helps break that cycle, which is a large part of why treating it matters so much.

The medicines that actively protect your kidneys

ACE inhibitors and ARBs do more than lower a number. They ease the pressure inside the kidney's filters and reduce the amount of protein leaking into the urine, which is why kidney specialists call them kidney protection medicines. For people with diabetes or protein in the urine, they are often the single most important tablet. A newer group, the SGLT2 inhibitors (such as empagliflozin and dapagliflozin), protect the kidneys too: in large trials they cut the risk of kidney disease getting worse by around a quarter, in people with and without diabetes.

Why your creatinine may rise, and why that is usually fine

Here is the part that causes the most worry. Soon after starting an ACE inhibitor or ARB, the creatinine on your blood test may tick up a little and your eGFR may dip. This is not the drug damaging your kidney. It reflects the medicine gently lowering the pressure inside the filter, which is exactly how it protects you. Guidelines accept a rise in creatinine of up to about 25 to 30% as expected, as long as it settles within a few weeks and your potassium is not too high. A larger or steadily climbing rise does need review, but a small bump is often a sign the medicine is working, not a reason to stop it.

The real risk: the "triple whammy"

There is one combination worth knowing about. Taking an ACE inhibitor or ARB together with a water tablet (a diuretic) and a common anti-inflammatory painkiller (an NSAID such as ibuprofen or diclofenac) is nicknamed the triple whammy, because together they can tip the kidneys into sudden injury. A review found this trio roughly doubles the risk of acute kidney injury. The lesson is not to fear your blood pressure tablets, but to be careful with over-the-counter painkillers and to drink enough, especially when you are unwell.

Using them safely

A few simple habits keep these medicines firmly on your side: take them as prescribed and never stop suddenly on your own; have the blood tests your doctor asks for (usually creatinine and potassium) after starting or changing a dose; reach for paracetamol rather than an anti-inflammatory for everyday aches; and during a spell of vomiting, diarrhoea or high fever, ask your doctor whether to pause the tablet for a day or two until you recover.

Blood pressure tablets are not the enemy of your kidneys. Taken steadily, checked now and then, and kept away from the wrong painkillers, they are one of the best ways to keep your kidneys working well for years to come.

This article is general information and not a substitute for personalised medical advice. If you are concerned about your kidney health, please consult a doctor.