Key takeaways:
The kidneys remove waste from the blood and play a key role in processing medications and supplements. This also means they’re more prone to harm with certain supplements.
If you have kidney disease, you need to be especially careful with supplements. Amounts that are safe for most people can be more harmful if you have kidney conditions.
No supplement has been proven to improve kidney health. In fact, some supplements can harm the kidneys even if you don’t have kidney problems.
Your body is great at getting rid of what it doesn’t need. And your kidneys play a big role in this process by filtering the blood and getting rid of waste through urine. They love it when you stay hydrated and eat a balanced diet. While many people look to supplements to boost kidney health, they aren’t needed. In fact, they can put an extra strain on the kidneys.
And if you have kidney disease, you should be extra cautious with supplements. Impaired kidney function can lead to toxic levels of supplements in the body.
What supplements are bad for kidneys?
There are thousands of individual supplements on the market, so we can’t cover them all here. But we’ll talk about some of the most common ones to avoid if you have bad kidneys. And a few that can potentially cause kidney damage, even if your kidneys are healthy.
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1. Protein
Protein is important for supporting metabolism and muscles, and eating normal amounts is usually fine. But even if you don’t have kidney disease, eating too much protein can be harmful. Studies show that more than 1.5 g of protein per kilogram of body weight each day can raise the risk of kidney disease.
People with known kidney disease usually need less protein than the general population. This is because their kidneys can’t clear protein waste as efficiently. If you have kidney disease, you should aim for no more than 0.8 g per kilogram per day. This means that if someone with kidney disease weighs 150 lbs, they shouldn’t have more than 55 g of protein a day. If you have more advanced disease, ask your kidney specialist if you should eat even less daily protein.
As with other nutrients, getting protein through food sources is the best. Protein powders are generally safe, but remember to read the full ingredients list and measure to make sure you’re getting the right amount.
2. Creatine
Creatine is a popular supplement to boost athletic performance. It’s also known as a supplement that supports healthy aging. It’s generally safe in standard dosages (3 g to 5 g per day). It can cause a small, temporary rise in serum creatinine, a marker of kidney function. But this isn’t associated with a decrease in true kidney function.
Experts advise against dosages higher than 3 g to 5 g of creatine per day if you have kidney disease. More research is needed to understand the effects of high-dose creatine in people with kidney disease. And since creatine can affect measurements of kidney function, monitoring can be challenging in people at risk for kidney disease due to conditions like diabetes or high blood pressure.
3. Aristolochic acid
Aristolochic acid is a plant compound found in certain Aristolochia (birthwort) plants. It’s also found in smaller amounts in Asarum (wild ginger). Wild ginger is completely different from the ginger root used in cooking, which is safe to eat.
Aristolochic acid has been used in herbal remedies for things like weight loss. But it can cause severe, permanent kidney damage. It may even raise the risk of certain cancers. Because of this, it’s banned or restricted in many countries. Even small amounts are unsafe and should be avoided.
4. Potassium
Potassium supplements don’t directly harm the kidneys. But people with kidney disease should avoid potassium supplements.
The kidneys keep potassium levels in a narrow range. This is because too much potassium can be dangerous and even lead to life-threatening heart issues. People with kidney disease are at increased risk of high potassium levels, and so they shouldn’t take potassium supplements. They may even need to limit their consumption of potassium-rich foods, such as avocados and lentils, since the kidneys may not be able to filter excess potassium.
5. Magnesium
Magnesium is an essential nutrient, and most people get enough from foods like beans, nuts, whole grains, bananas, and leafy greens. Women should get about 320 mg per day, and men should get about 420 mg per day. There are many types of magnesium supplements, but most healthy people don’t need them. But if you have kidney disease, you definitely should steer clear of supplements.
Like potassium, the kidneys control magnesium levels. And if your kidneys aren’t working well, extra magnesium from supplements can build up in your body. If you have chronic kidney disease (CKD), only take magnesium supplements if someone on your healthcare team says you need them.
6. Others
Some other herbal supplements linked to kidney damage include:
Thunder god vine (Tripterygium wilfordii)
Impila (Calliliepis laureola)
St. John’s wort (Hypericum perforatum) — can interact with medications and affect drug levels
Wormwood (Artemisia herba-alba)
Tribulus (Tribulus terrestris)
Cat’s claw (Uncaria tomentosa)
Licorice (Glycyrrhiza glabra)
Chinese ephedra or ma huang (Ephedra sinica)
Aloe vera (when eaten)
Senna (chronic use can lead to dehydration and kidney stress)
Cáscara sagrada (Rhamnus purshiana)
Rhubarb root (can contribute to kidney stone formation and injury)
Chromium supplements (avoid all forms in high doses)
Starfruit (contains high levels of oxalates and a neurotoxin that can build up in people with kidney disease)
These should be used with caution in healthy individuals and are best avoided entirely in those with CKD.
What vitamins can be hard on the kidneys?
Just like supplements, not all vitamin supplements are necessary or safe. Some vitamins can dissolve in water. If your body doesn’t need them, usually they can be excreted in the urine. This is the case with so-called “water-soluble” vitamins (B, C, E).
Other vitamins are stored in fat (A, D, E, K). It’s important not to take too much of those since they can build up in the body and become harmful.
People who have kidney disease are at risk of having low vitamin stores. This is due to changes in appetite, dietary restrictions, or loss of nutrients through dialysis. Still, not everyone with kidney disease should take vitamins — and some vitamins can be especially harmful.
1. Vitamin C
Katherine Toma, DO, is a nephrologist who specializes in kidney disease. She cautions her patients against taking too much vitamin C.
While vitamin C itself isn’t harmful, the body converts extra vitamin C to oxalate. Oxalate can join with calcium to form crystals that block the kidneys (kidney stones). Large doses of vitamin C can also interfere with urine tests, leading to missed diagnoses.
People with CKD at risk for vitamin C deficiency should stick to less than 100 mg per day.
2. Vitamin A
Kidneys are responsible for filtering vitamin A, and levels are often high in people with CKD. Standard doses of vitamin A in supplements can build up to harmful levels, even for people on dialysis. Because of this, vitamin A supplements aren’t recommended for people with CKD.
3. Vitamin E
Vitamin E is fat soluble and can build up in people with CKD. High levels may raise the risk of bleeding and hemorrhagic stroke. Supplements can also interfere with blood thinners. For this reason, people with CKD aren’t usually advised to take vitamin E supplements.
4. Multivitamins
Multivitamins are usually safe for people with normal kidneys in the recommended daily dosage. But avoid them if you have kidney issues. Multivitamins contain some micronutrients that people with kidney disease should avoid. Your kidney specialist will screen for vitamin deficiencies and recommend supplementation as needed.
What OTC medications can be bad for your kidneys?
If you don’t have kidney problems, taking over-the-counter (OTC) medications as directed is usually safe. But even if you have healthy kidneys, some OTC medications can be harmful if you take too much. And people with kidney disease should take extra care, even at normal dosages.
1. NSAIDs
Nonsteroidal anti-inflammatory drugs (NSAIDs) are medications used to treat pain and inflammation. They’re available with or without a prescription, and are a common medication in most people’s medicine cabinets. But they can damage the kidneys, especially at higher than recommended dosages.
Some risk factors for kidney damage are chronic kidney disease (CKD) and dehydration. Taking NSAIDs at the same time as other medications that are filtered by the kidneys — such as some blood pressure medications or diuretics (water pills) — can also increase the risk of kidney damage. So those with CKD should ask their healthcare team before taking recommended dosages of NSAIDs.
2. Proton pump inhibitors (PPIs)
Proton pump inhibitors (PPIs) are OTC medicines for heartburn. They can cause a kidney problem called acute interstitial nephritis (AIN), which can get better if treated. Although this problem is rare, it can happen at any time and even with standard doses.
Some studies suggest PPIs may raise the risk of kidney disease or make it worse, but other studies don’t suggest so. And more research is needed to see if PPIs play a direct part in kidney disease.
If you have kidney disease, your healthcare team may advise against using PPIs. If you have had AIN from PPIs before, you shouldn’t take them again.
How can you tell if supplements are causing kidney damage?
Signs of kidney damage are often subtle and may only show up on tests. You might notice:
Frothy urine
Decrease in the amount of urine
Tell someone on your healthcare team if you experience these symptoms. They may recommend blood and urine tests to see how well the kidneys are filtering.
Frequently asked questions
If you have kidney disease, never take a supplement without checking with your kidney specialist first. There are no herbal remedies that can help or cure kidney problems. Even substances marketed as “natural” or “herbal” can be harmful. Herbal supplements may also contain added vitamins or minerals that are risky for people with chronic kidney disease (CKD).
It depends. Low vitamin D in people with kidney disease is linked to disease progression. But most people get enough vitamin D from sun exposure and diet. And too much can be toxic. If you don’t have risk factors or symptoms of vitamin D deficiency, you don’t need routine vitamin D testing. Talk with a healthcare professional about the need to screen. They can also recommend how much to take based on your levels.
If you have kidney disease, never take a supplement without checking with your kidney specialist first. There are no herbal remedies that can help or cure kidney problems. Even substances marketed as “natural” or “herbal” can be harmful. Herbal supplements may also contain added vitamins or minerals that are risky for people with chronic kidney disease (CKD).
It depends. Low vitamin D in people with kidney disease is linked to disease progression. But most people get enough vitamin D from sun exposure and diet. And too much can be toxic. If you don’t have risk factors or symptoms of vitamin D deficiency, you don’t need routine vitamin D testing. Talk with a healthcare professional about the need to screen. They can also recommend how much to take based on your levels.
The bottom line
The best way to protect your kidneys is to eat a balanced diet and live a healthy lifestyle. Most people don’t need supplements, and there isn’t strong evidence to support taking them regularly.
If you have symptoms of a nutritional deficiency, a special diet, or kidney disease, ask your healthcare team about targeted testing. Some supplements and vitamins can even be harmful, especially in those with kidney disease. And if a supplement makes claims that seem too good to be true, it probably is. As always, check with your healthcare team before taking something new.
Why trust our experts?
References
Brown, A. M. (2017). Kidney toxicity related to herbs and dietary supplements: Online table of case reports. Part 3 of 5 series. Food and Chemical Toxicology.
Han, J., et al. (2019). Systematic overview of aristolochic acids: Nephrotoxicity, carcinogenicity, and underlying mechanisms. Frontiers in Pharmacology.
Heymsfield, S. B., et al. (2024). Guidance on energy and macronutrients across the life span. The New England Journal of Medicine.
Ikizler, T. A., et al. (2020). KDOQI clinical practice guideline for nutrition in CKD: 2020 update. American Journal of Kidney Diseases.
Ko, G. J., et al. (2020). The effects of high-protein diets on kidney health and longevity. Journal of the American Society of Nephrology.
Naeini, E. K., et al. (2025). Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrology.
National Institute of Diabetes and Digestive and Kidney Diseases. (2025). Healthy eating for adults with chronic kidney disease. National Institutes of Health.
Neto, M. M., et al. (2009). Star fruit: simultaneous neurotoxic and nephrotoxic effects in people with previously normal renal function. NDT Plus.
