When experiencing back pain, headache or muscle pain, the reaction is automatic: take medicine. Often, the drug in question is an anti-inflammatory – which even alleviates the discomfort, but not without risk. This seemingly banal habit can be harmful, especially to the kidneys and heart.
Self-medication is very common in the country. According to a 2024 survey by the (Institute of Science, Technology and Quality), around 9 out of 10 Brazilians take medication on their own. A significant portion of these medications belong to the group of NSAIDs (non-steroidal anti-inflammatory drugs), such as ibuprofen, diclofenac and naproxen.
DANGEROUS TRIAD AND INTERACTIONS
The risk may be even greater when anti-inflammatories are used with certain medications, something common among hypertensive or heart patients. The call “dangerous triad” involves anti-inflammatories, diuretics and blood pressure medications, such as ACE (angiotensin-converting enzyme) inhibitors or angiotensin receptor blockers.
Each of these drugs interferes with a part of the system that regulates blood filtration by the kidneys. When used together, they can drastically reduce the pressure needed for organs to function, so that they simply stop filtering blood properly.
Other combinations can also affect the kidneys, such as NSAIDs with SGLT2 inhibitors (dapagliflozin, empagliflozin, canagliflozin), medications used for diabetes, heart failure and chronic kidney disease; with lithium, used to treat and prevent episodes of mania and depression in bipolar disorder; and with cyclosporine, indicated to treat serious autoimmune and inflammatory diseases, such as psoriasis, atopic dermatitis, rheumatoid arthritis, nephrotic syndrome and uveitis.
The combination can also reduce the effect of antihypertensive medications, which affects the treatment of those with high blood pressure. NSAIDs can also enhance the effects of anticoagulants and antiplatelet agents, increasing the risk of bleeding and hemorrhage.
WHAT HAPPENS IN THE KIDNEYS
The kidneys act as a continuous blood filtration system, functioning 24 hours a day. To carry out this work, they require adequate internal pressure.
NSAIDs block the production of prostaglandins, substances that function as “pressure maintainers” inside the kidneys, keeping the blood vessels open and well irrigated.
“When these prostaglandins are blocked, the vessels that supply blood to the kidney contract. The kidney receives less blood and filters less. In healthy people, this is usually temporary and reversible, but in those who already have a kidney problem, high blood pressure, diabetes or advanced age, this reduction can be enough to cause serious damage”explains nephrologist Patricia Taschner Goldenstein, from .
A cross-sectional study carried out at the Hospital das Clínicas (Federal University of Pernambuco) revealed that 14.8% of patients with chronic kidney disease used NSAIDs, many of them self-medicating. The main reasons were rheumatic and musculoskeletal pain, which often leads to repeated use of these medications.
In these groups, the kidneys function with “margin of safety” reduced. In people with hypertension or diabetes, for example, the small renal vessels often already have damage, a process called microangiopathy. The kidneys still function, but they have less reserve to face stressful situations.
In the elderly, there is a natural age-related decline in kidney function. From the age of 40, it is estimated that there will be a loss of around 10% of kidney function per decade, although this can vary. A 70-year-old person may only have 70% of the kidney function of a young person, even though they are apparently healthy.
In these cases, even a single dose of an anti-inflammatory drug is capable of triggering acute kidney failure, when the organ stops functioning suddenly, but can still recover if the drug is stopped quickly. However, if use is prolonged, it can lead to chronic nephropathy, when the kidney develops permanent damage, with fibrosis and tissue scarring, which can progress to end-stage renal disease, requiring dialysis or transplant.
“Prolonged use is dangerous even for healthy kidneys, with an increased risk of developing chronic kidney disease, even in people without previous risk factors such as diabetes, high blood pressure, obesity and advanced age”warns Goldenstein.
SILENT DISEASE
Another problem is that chronic kidney disease usually progresses in silence. “It is estimated that around 90% of people in the early stages do not know they have the disease”reports the nephrologist.
“When someone with already compromised kidneys takes anti-inflammatories regularly, they are accelerating the loss of kidney function without realizing it,” warns Goldenstein.
When symptoms appear, they may include foamy urine, reduced urinary volume, swelling in the legs or around the eyes, nausea, lack of appetite and unexplained tiredness. In many cases, the first warning only appears when kidney function is already compromised, which also includes signs such as blood in the urine and mental confusion.
IMPACTS ON THE HEART AND OTHER ORGANS
The effects of prolonged use of non-steroidal anti-inflammatory drugs are not limited to the kidneys. From a cardiovascular point of view, they are far from harmless.
“The use of anti-inflammatories generally leads to greater salt and water retention, and this can lead to an increase in blood pressure”notes cardiologist Carlos Eduardo Montenegro, vice-president of the Clinical Cardiology department of the (Brazilian Society of Cardiology).
The worsening of kidney function itself also has this effect, impacting the heart. In people with heart disease, the risk may be even more serious. “It is very common for use for a period of time a little longer than a few days to lead to decompensation of coronary disease, such as angina events or even acute myocardial infarction”, reports Montenegro.
Prolonged use can also affect organs such as the stomach and liver, which can lead to ulcers and hepatitis, especially in elderly people or people with previous complications. Therefore, the use of NSAIDs must be done with caution, at the lowest effective dose and for the shortest possible time.
On the other hand, there are safer alternatives when used correctly. Paracetamol and muscle relaxants are some examples. “The choice of the ideal treatment depends on the type of pain, the patient’s clinical conditions and an individualized assessment.”Guids Patricia Goldenstein.
But the main point is not just to change medicine. “The most important thing is to identify the cause of the pain. Treating the source of the problem is always better than just suppressing the symptom with medication indefinitely”, advises Einstein’s doctor.
This text was originally published by Agência Einstein on April 6, 2026 and adapted for publication by Poder360.
