When we reach the age designation known as a “senior citizen,” a lot of things in our bodies have already changed. Our visual acuity, hearing, body shape, and weight are drastically different. What hair we men have left on our scalp has turned gray or white. The skin on our faces suddenly has new lines and wrinkles, and body parts that had a specific location are now sagging. These are the obvious, visible changes we recognize as caused by aging and other biologic factors.
But what about changes we can’t see. The changes occurring in our internal organs, arteries, and veins, hidden from awareness and progressing slowly, doing harm we often learn about too late. One example is arteriosclerosis, hardening of the arteries. During WWII, autopsies done on soldiers killed in combat showed sclerotic plaques in their major arteries. It was then that doctors learned arteriosclerosis begins in our early twenties and smolders along until it gets bad enough to cause symptoms. Another silent change occurs in the kidneys which are affected by numerous medications and cause no symptoms until they are close to failure.
The majority of prescription drugs are eliminated by the kidneys. Because of that, many medications can harm kidney function, and it can decline to Stage IV or Stage V before the patient is aware of it. In today’s healthcare climate, most patients are taking multiple medications, many of which are harmful to the kidneys. Knowing which drugs are and aren’t nephrotoxic (harmful to kidney function) is important for both patients and doctors. As Hippocrates stated, “abstain from all intentional wrong-doing and harm…..either help or do not harm the patient.” Even with this acknowledgement, doctors still prescribe drugs that may harm the kidneys. They do this because it’s the best drug for the situation, they don’t think it will harm the kidneys, or they simply didn’t check if it does.
On March 17, Medscape, the reference source I use most often, published a list of ten “widely used medications” that affect kidney function and should be monitored to prevent them from affecting the kidneys. This is especially important for patients who already have evidence of chronic kidney disease based on prior lab testing. Two of these medications are available over-the-counter and thus are indiscriminately taken by more people unaware of the effect on their kidneys. Below I have listed all ten drugs, but will discuss only those used frequently. Drugs that are harmful to the kidneys are:
NSAID’s (Non-Steroidal Anti-inflammatory Drugs): Non-steroidals are the drugs that affect kidney function more often than any others. Available OTC as well as by prescription, they treat the inflammation of arthritis and pain of many types. Millions of doses are taken every day, and the kidneys of millions of patients are affected. Ibuprofen, naproxen, diclofenac, celecoxib, meloxicam, indomethacin, etc. affect blood flow to the kidneys and the glomeruli, the kidney’s filtering units. They also cause inflammation and swelling of the filtering tubules (interstitial nephritis). Kidney function tests (BUN, GFR, Creatinine) can be affected severely. Any patient with CKD (Chronic Kidney Disease) should avoid taking NSAID’s. Long term NSAID use without monitoring kidney function can permanently affect kidney function.
ACE’s (Angiotensin Converting Enzyme Inhibitors):
ARB’s (Angiotensin Receptor Blockers):
These are two classes of drugs for high blood pressure. Alone, each of these drugs preserves kidney functioņ, especially in diabetics. But ACE’s can cause elevated potassium levels. Taken together, ACE’s and ARB’s raise potassium and creatinine levels, ie. reduce kidney function. Monitoring of kidney function is very important.
DIURETICS: (“Water Pills”) They lower BP by reducing the volume of fluid in the bloodstream and relaxing smooth muscle in blood vessel walls. They harm the kidneys by the same mechanism (dehydration) and also cause imbalances of sodium and potassium. Diuretics are added to ACE’s and ARB’s in combination drug therapy compounding the potential for kidney damage. Monitoring kidney function tests twice a year heads off kidney failure before it reaches irreversability.
PROTON PUMP INHIBITORS: Used for esophageal reflux, esophagitis, gastritis, H. pylori bacterial infection. Studies have shown long term use of PPI’s has increased the risk for CKD. Intermittent dosing is recommended.
METFORMIN: Used for diabetes. It accumulates in bloodstream and reduces GFR (kidney function test). Recommend frequent monitoring of kidney function tests.
SULFAMETHOXAZOLE/TRIMETHOPRIM (SMZ-TMP, Bactrim, Septra): Commonly used antibiotic for treatment of urinary tract infections. It can elevate the potassium, decrease GFR. It can also cause a hypersensitivity reaction which damages the kidneys.
ALLOPURINOL: Used to lower serum uric acid levels in gout patients. It can cause allopurinol kidney hypersensitivity reaction which damages the tubules. It also has direct toxicity to the kidney. Unless absolutely necessary, patients with CKD should not take allopurinol. Monitoring kidney function regularly is a necessity.
SGLT2 INHIBITORS: Drugs for diabetes that protect the kidneys and heart. It may cause a small decline in GFR and dehydration, so kidney function needs monitoring.
ACYCLOVIR, VALYCYCLOVIR: Drugs used to treat Herpesvirus infections. Can cause acute kidney injury due to forming crystals that plug up the tubules. Kidney function should be monitored regularly.
LITHIUM: Used to treat bipolar disorder. Has the potential to damage kidney tubules and cause diabetes insipidis (excess urine output due lack of anti-diuretic hormone). Requires regular monitoring of kidney function.
Dr. G’s Opinion: NSAID’s, ACE’s, ARB’s, diuretics, PPI’s, and metformin are the biggest offenders of kidney function because they are all used often for maintenance therapy of chronic diseases. When you take one or more of these drugs, monitoring of the kidney function should be done twice a year. At the first indication of declining kidney function, the offending drugs should be discontinued or the dose altered. This is a common problem so if you’re on any one of these 10 medications, you need to be certain to have a metabolic panel done. That should include a Chem-12 to include BUN, Creatinine, GFR, and electrolytes, plus a CBC, Urinalysis.
Reference: Hannedouche T. Polypharmacy in Chronic Kidney Disease: 10 Drugs Clinicians Must Monitor Medscape 2026 March 17.
