A common painkiller found in many medicine cabinets may become risky when it is combined with certain blood pressure medicines.
Researchers at the University of Waterloo found that taking ibuprofen together with two widely used types of blood pressure drugs may raise the risk of sudden kidney injury in some people.
The concern involves people taking a diuretic and a medicine that acts on the renin-angiotensin system, or RAS. These medicines are often prescribed to control high blood pressure and protect people from serious problems linked to the heart and blood vessels.
Diuretics are sometimes called “water pills” because they help the kidneys remove extra salt and water from the body. This reduces the amount of fluid circulating through the blood vessels and can help lower blood pressure.
RAS medicines include commonly prescribed drugs such as ACE inhibitors and angiotensin receptor blockers. They affect a hormone system that helps control blood pressure, fluid balance and blood flow through the kidneys.
Both types of medicine can be very useful when taken as prescribed. The problem may appear when a person taking them also uses ibuprofen, a widely available pain reliever used for headaches, muscle pain, arthritis, fever and other common problems.
Ibuprofen belongs to a family of medicines called nonsteroidal anti-inflammatory drugs, usually shortened to NSAIDs. These medicines reduce pain and inflammation, but they can also change blood flow inside the kidneys.
Professor Anita Layton and colleagues at the University of Waterloo used detailed computer models to investigate what happens when the three types of medicine are combined. Their research was published in the journal Mathematical Biosciences.
The models showed that the combination could make some people more likely to develop acute kidney injury. This is a sudden decline in the kidneys’ ability to filter waste and maintain the body’s normal balance of water and chemicals.
The kidneys need a steady supply of blood to work properly. Diuretics can reduce the amount of fluid in the body, while RAS medicines change pressure within the tiny blood vessels involved in kidney filtration.
Ibuprofen can affect another mechanism that helps maintain blood flow to the kidneys. When all three effects occur together, kidney filtration can fall sharply, particularly when a person is already dehydrated or has other factors that make the kidneys more vulnerable.
This three-drug combination is sometimes described as a “triple whammy.” The name reflects the way three different medicines can work together to place extra stress on the kidneys, even though each medicine may be appropriate when used in the right circumstances.
The researchers emphasized that taking these medicines together does not mean everyone will develop kidney damage. Individual risk can depend on factors such as kidney health, hydration, age, other illnesses and the medicines a person is taking.
The findings are especially important because ibuprofen is available without a prescription in many places. People may therefore see it as harmless and may not think to mention it when discussing their medicines with a doctor or pharmacist.
People taking blood pressure medicines should not stop prescribed treatment because of this research. Instead, anyone taking a diuretic together with an ACE inhibitor, angiotensin receptor blocker or another RAS medicine should check with a health professional before adding ibuprofen or another NSAID.
Paracetamol, known as acetaminophen in the United States, may sometimes be considered as an alternative for pain relief because it works differently. However, the best choice depends on a person’s health, other medicines and the reason for the pain, so professional advice is still important.
The study highlights a broader lesson about everyday medicines. A drug being available without a prescription does not mean it is safe for every person or safe in every combination.
For people living with high blood pressure or other long-term conditions, checking possible drug interactions can be an important part of protecting kidney health. A quick conversation with a doctor or pharmacist before taking a new painkiller may help prevent a potentially serious problem.
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