If you have kidney disease, be careful with supplements. This is especially important for people with rare conditions like C3 glomerulopathy (C3G) and immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN). These conditions can harm the kidneys by affecting the immune system. Some vitamins, minerals, and herbal products may weaken kidney function or interfere with medications. If you have kidney disease, are on dialysis, or take certain drugs, some supplements could do more harm than good.

Here are 10 facts you need to know about supplements that may be dangerous for your kidneys and what to consider before taking them.

1. Creatine Can Stress Your Kidneys

Creatine is a substance found in muscles that helps the body make energy. Many people take it as a supplement to build muscle and improve exercise performance, but it may put extra stress on the kidneys, especially for those with kidney disease. It can raise blood levels of creatinine (a waste product with a similar name), which can make it look like kidney function is worse, even if it’s not causing damage. People with kidney disease should avoid creatine unless a doctor says it’s safe.

Using creatine supplements for a long time — especially in combination with other medications and caffeine — can lead to dehydration, which may contribute to kidney problems. If you have kidney disease and are an athlete or a bodybuilder, talk to your doctor about safer alternatives.

2. High-Dose Vitamin C Can Lead to Kidney Stones

Vitamin C is important for health, but taking too much, especially more than 2,000 milligrams per day, can lead to kidney stones. Extra vitamin C can turn into a substance called oxalate (a waste product that the body gets rid of through urine), which can build up in the kidneys and cause stones, especially in people with kidney disease.

Oxalate buildup can make kidney problems worse. To support your immune system safely, it’s better to get vitamin C from foods like oranges, strawberries, and bell peppers instead of taking high-dose supplements.

3. Calcium Supplements May Increase Kidney Stone Risk

Calcium helps keep bones strong, but too much from supplements (not food) can cause kidney stones. Getting calcium from food is safer for kidney health than taking pills. Extra calcium from supplements can build up in the blood, leading to calcification (hardening of the kidneys and blood vessels due to calcium deposits). Instead, try getting calcium from dairy products, leafy greens, and fortified (nutrition-boosted) foods.

4. Potassium Supplements Can Be Dangerous

People with chronic kidney disease (CKD) often have trouble keeping potassium levels balanced. Too much potassium from supplements can cause heart rhythm problems or even a heart attack. If you have CKD, avoid potassium supplements unless prescribed by a doctor.

Some foods naturally contain a lot of potassium, including bananas, avocados, and potatoes. If you need to manage potassium levels, it’s best to work with a dietitian to create a kidney-friendly eating plan instead of relying on supplements.

5. NSAIDs and Herbal Anti-Inflammatories Can Harm the Kidneys

Some herbal supplements, like turmeric and willow bark, act like nonsteroidal anti-inflammatory drugs (NSAIDs), which help reduce pain and swelling. While turmeric is sometimes recommended for kidney health, taking large amounts can damage the kidneys, especially in people with C3G, IC-MPGN, or advanced kidney disease.

NSAIDs, like ibuprofen (Advil, Motrin) and naproxen (Aleve), can reduce blood flow to the kidneys, making kidney function worse over time. If you need pain relief, discuss safer alternatives with your doctor.

6. St. John’s Wort Can Interfere With Kidney Medications

St. John’s Wort is a supplement used for depression, but it can weaken the effects of many medications, including those for kidney disease and people who have had transplants. St. John’s Wort has even been linked to an increased risk of organ rejection in people with kidney transplants.

If you have kidney disease and are experiencing depression or anxiety, it’s best to talk to a doctor about safe treatment options instead of using over-the-counter supplements.

7. Protein Supplements Can Overwork Kidneys

High-protein diets and protein powders can be harmful to people with kidney disease. Too much protein causes waste buildup in the blood, forcing the kidneys to work harder. People with kidney disease may need to limit protein intake based on their doctors’ recommendations.

People on dialysis may need more protein, but a healthcare provider should always monitor the type and amount. Instead of protein powders, try lean meats, eggs, and beans in controlled portions.

8. Herbal Supplements Like Licorice Root Can Raise Blood Pressure

Licorice root is used for digestion and breathing problems, but it contains glycyrrhizin (a natural compound) that can lead to high blood pressure, low potassium, and kidney damage.

Even in small amounts, licorice can worsen fluid buildup in the body, which is a common problem for those with kidney disease. Always check ingredient labels, as licorice extract is often found in teas and herbal blends.

9. Vitamin D Supplements Need Monitoring

Vitamin D can be helpful in safe, balanced amounts, but too much can lead to kidney calcification. Some people with kidney disease need special forms of vitamin D to support bone health and prevent deficiencies. However, others may need to limit vitamin D supplements because excess amounts can lead to high calcium levels, increasing the risk of calcification. If you need a supplement, stick to doctor-recommended doses.

10. Taking Supplements Without a Doctor’s Advice Can Be Risky

Many supplements say they are “kidney-friendly,” but even natural supplements can be harmful. Herbal and over-the-counter supplements may interact with medications or worsen kidney disease. The safest option is to ask your doctor, pharmacist, or nephrologist (kidney specialist) before taking any new supplement.

Are Any Supplements Good for Kidney Health?

While some supplements are harmful, a few may help kidney health if taken under a doctor’s guidance. For example:

• Omega-3 fatty acids may slow worsening of kidney function, but more research is needed.
• Probiotics help gut health and may lower waste buildup in the blood.
• B vitamins help with energy and metabolism but should be taken in safe amounts to avoid excessive buildup in kidney disease.
• CoQ10 may protect the kidneys by reducing oxidative stress (damage caused by harmful molecules in the body), though evidence is mixed.

Other Points To Consider

Medication Interactions

Some supplements can interfere with kidney medications, making them less effective or causing harmful side effects. Certain ingredients may weaken medications, increase side effects, or create dangerous imbalances in minerals like potassium or calcium.

Dialysis and Supplements

Dialysis changes how your body processes nutrients, which means some supplements can build up in your blood instead of being filtered out. High levels of potassium, phosphorus, or magnesium can cause serious complications.

Dosage Matters

Even supplements labeled as “safe” can be harmful in high doses. Taking more isn’t always better — too much of certain vitamins and minerals can be toxic. Always follow your doctor’s recommended dosage to avoid health risks.

Natural Doesn’t Mean Safe

Just because a supplement is herbal or plant-based doesn’t mean it’s good for kidney health. Some herbal products can strain the kidneys, increase blood pressure, or interfere with medications. Before using any supplement, always consult a doctor, pharmacist, or nephrologist to ensure it’s safe for you.

Ask Your Doctor

When it comes to supplements and kidney health, it’s always best to check with your doctor before taking anything new. Some supplements can be helpful, but others can be harmful, especially if you have kidney disease or are on dialysis. Even natural or over-the-counter products can interfere with medications or cause serious health problems. To stay safe, talk to your healthcare provider about the best choices for your condition.

Talk With Others Who Understand

On MyKidneyDiseaseTeam, the social network for people with rare kidney diseases and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with rare kidney disease.

Are you taking supplements while living with kidney disease? Share your experience in the comments below, or start a conversation by posting on your Activities page.