Many medications are safe and highly beneficial when used correctly. But because the kidneys help filter drugs and their byproducts from the body, certain medicines can become dangerous when they are taken at the wrong dose, used for too long, combined with other drugs, or taken when the kidneys are already vulnerable.
The risk can be particularly important for people with chronic kidney disease, diabetes, high blood pressure, dehydration, heart disease, or reduced kidney function.
Here are eight medication groups worth knowing about—and why self-medicating can sometimes cause problems.
1. Ibuprofen and Other NSAID Painkillers
Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most important medications to watch.
Common examples include:
- Ibuprofen
- Naproxen
- Diclofenac
- High-dose aspirin
NSAIDs can reduce blood flow through the kidneys. High doses or prolonged use can increase the risk of acute kidney injury and worsening kidney function, particularly in people who already have kidney disease.
The risk can become greater when someone is dehydrated, has low blood pressure, or takes certain blood-pressure medicines.
That doesn’t mean everyone must avoid NSAIDs. Occasional use may be appropriate for some people, but people with kidney disease should discuss them with a healthcare professional before using them.
2. Certain Antibiotics
Antibiotics can be lifesaving when used for the right infection, but some can affect kidney function or accumulate in the body when kidney function is reduced.
Some antibiotics also require a dose adjustment based on kidney function. The National Kidney Foundation notes that certain infection medicines can cause kidney injury or produce additional side effects when levels become too high.
This is one reason leftover antibiotics or someone else’s prescription should never be used for self-treatment.
3. Proton Pump Inhibitors (PPIs)
Proton pump inhibitors are widely used to treat acid reflux and stomach ulcers. Examples include:
- Omeprazole
- Esomeprazole
- Lansoprazole
- Pantoprazole
These medicines can be appropriate and effective, but the National Kidney Foundation notes that kidney-related risks are more relevant with long-term use, particularly over many months or years. Potential concerns include acute kidney injury and other complications.
If you regularly take a PPI, don’t stop it suddenly on your own. Instead, ask your healthcare professional whether you still need it and whether your treatment should be adjusted.
4. Lithium
Lithium is an important prescription medicine used for certain mental health conditions. However, prolonged or higher-dose treatment can affect the kidneys.
Long-term lithium exposure can cause problems with the kidneys’ ability to concentrate urine and may increase the risk of chronic kidney disease. Regular monitoring of lithium levels and kidney function can help reduce the risk.
People taking lithium should never change their dose or stop treatment without medical guidance.
5. Some Antiviral and Antifungal Medicines
Certain antiviral and antifungal medications are processed or eliminated through the kidneys. Some can also cause kidney-related side effects.
This doesn’t mean these medicines are inherently unsafe. In many cases, they can be used successfully with the appropriate dose and monitoring. But people with reduced kidney function may need a different dose or dosing schedule.
That’s why healthcare professionals should know if you have kidney disease before prescribing these medications.
6. Certain Diuretics (“Water Pills”)
Diuretics are commonly prescribed to help control blood pressure or remove excess fluid.
They can be extremely useful, but they also change how much water and electrolytes leave the body. During illnesses involving vomiting, diarrhea, or significant dehydration, the combination of fluid loss and certain medications can put additional stress on the kidneys.
NIDDK specifically advises people taking medicines that affect kidney blood flow to have a plan for medication management when they become sick or dehydrated.
Never change a prescribed diuretic dose without discussing it with your healthcare professional.
7. ACE Inhibitors and ARBs—Especially During Dehydration
This category requires an important clarification.
Medicines such as lisinopril and losartan are commonly used to treat high blood pressure and can actually help protect kidney function in many people with conditions such as hypertension or diabetes.
However, when someone becomes significantly dehydrated or develops very low blood pressure, these medicines can contribute to a temporary decline in kidney filtration.
So these medicines should not be labeled as simply “bad for the kidneys.” They can be highly beneficial when appropriately prescribed, but certain illnesses and medication combinations require medical advice.
8. Some Medicines Used Before Certain Medical Tests
Certain medications and preparations used around medical procedures can also create kidney concerns in vulnerable people.
For example, the National Kidney Foundation warns that oral sodium phosphate preparations used for bowel cleansing before colonoscopy can cause serious kidney problems in people with certain risk factors, including existing kidney disease and some medication combinations.
This is why your doctor should know about all your medications before a procedure—not just your prescription drugs.
Why Self-Medicating Can Be Risky
The biggest problem isn’t simply that a medication exists. It’s how and why it is being used.
Self-medicating can lead to:
- Taking too high a dose
- Taking a medicine for too long
- Combining medicines with similar ingredients
- Taking an NSAID while dehydrated
- Using a drug that isn’t appropriate for your kidney function
- Missing dangerous drug interactions
- Taking someone else’s prescription
- Continuing an OTC medicine without realizing it contains an NSAID
Another problem is that many people don’t know their current kidney function. Kidney disease can develop gradually and may cause few obvious symptoms in its early stages.
Read the Active Ingredients
Brand names can make medication safety confusing.
Two different products may contain the same active ingredient, meaning you could accidentally take more than intended.
This is particularly important with pain relievers and cold or flu products.
Check the active ingredients on the label and ask a pharmacist if you’re unsure.
Who Should Be Especially Careful?
Talk with a healthcare professional or pharmacist before using potentially kidney-affecting medicines if you have:
- Chronic kidney disease
- Diabetes
- High blood pressure
- Heart disease or heart failure
- A history of acute kidney injury
- Dehydration from vomiting or diarrhea
- An older age with multiple medications
- A kidney transplant
The National Institute of Diabetes and Digestive and Kidney Diseases recommends keeping an updated list of all prescriptions, OTC medicines, vitamins, and supplements and reviewing them with your healthcare team.
What You Should Do Instead of Self-Medicating
Before starting a new medication, ask:
“Is this safe for my kidneys?”
Also ask whether the dose needs to be adjusted for your kidney function and whether it interacts with anything else you’re taking.
A pharmacist can be particularly helpful when you’re purchasing an over-the-counter medicine.
And if you already have kidney disease, your eGFR—a measure of kidney filtration—is often important when determining whether a medication or dose is appropriate.
Don’t Stop Important Medicines Suddenly
Learning about medication risks shouldn’t make you afraid to take prescribed treatment.
Some medicines that have potential kidney-related risks are also essential for treating serious conditions. Stopping them suddenly can create different and sometimes more serious problems.
Instead, discuss concerns with your doctor or pharmacist before changing a prescribed medication.
Final Thoughts
Your kidneys process many of the medicines that enter your body, so medication safety is especially important when kidney function is reduced.
NSAIDs such as ibuprofen and naproxen deserve particular caution, while certain antibiotics, PPIs, lithium, antiviral or antifungal medicines, diuretics, and other treatments may require individualized dosing or monitoring.
The key message isn’t to avoid medications altogether. It’s to use the right medicine, at the right dose, for the right amount of time—and to avoid self-medicating when you aren’t sure what’s safe for you.
If you have kidney disease or take several medications, a pharmacist or healthcare professional can review your complete medication list and identify potential kidney-related risks.