Can MSM Harm Your Kidneys? A Careful Look at the Limited Data

The short answer: no kidney-harm signal was detected, but the evidence is thin

Available evidence does not demonstrate that methylsulfonylmethane (MSM) causes kidney damage. It is also too limited to prove that MSM is safe for every person, product, dose, duration, or kidney-related circumstance.

The most relevant human evidence is a controlled safety analysis in which participants took 6 grams of MSM daily for 16 weeks. Researchers reported no significant difference in serum creatinine between the MSM and placebo groups. Both groups also took naproxen. This is reassuring within those narrow study conditions, but it means only that the trial did not detect a creatinine difference—not that MSM can never affect the kidneys. The accessible trial abstract reports the study design and stated laboratory findings.

General medical references primarily list digestive effects, rash, and allergic reactions as possible MSM side effects. Kidney injury is not identified as an established adverse effect in those references, although omission from a side-effect list cannot prove that kidney harm is impossible. Cleveland Clinic, for example, lists constipation, diarrhea, upset stomach, rash, hives, and other allergic symptoms while cautioning that its lists may not cover every possible reaction. Its MSM monograph also advises users to discuss supplements and possible interactions with their care team.

The evidence therefore supports four limited conclusions:

• No kidney-harm signal was detected in the human evidence reviewed.
• MSM has not been proven universally safe for the kidneys.
• Long-term and rare renal risks remain uncertain.
• Safety has not been adequately established in chronic kidney disease, dialysis, kidney-transplant recipients, or people recovering from acute kidney injury.

If you have reduced kidney function, chronic kidney disease, a previous acute kidney injury, a kidney transplant, or receive dialysis, seek individualized advice before using MSM. The same applies if you take several medicines or supplements. This caution reflects missing direct safety and dosing evidence for higher-risk users—not proof that MSM damages their kidneys.

Editorial note: Bulk MSM describes itself as an independent educational site, not a supplement seller or medical provider. Its terms of use advise readers to consult a doctor before starting a supplement.

What the principal kidney-relevant human trial actually measured

The most directly relevant human study identified in the reviewed evidence was a randomized, double-blind, placebo-controlled safety analysis involving 100 people with osteoarthritis and low back pain. Fifty participants received MSM plus naproxen, while 50 received placebo plus naproxen. The MSM group took 6 grams per day of OptiMSM for 16 weeks. Kidney assessment centered on serum creatinine. Blood counts, glucose, liver markers, body weight, and blood pressure were also measured, and the accessible abstract reports no significant between-group differences in those variables. Bergstrom Nutrition supplied the MSM and placebo but reportedly had no role in the trial design or review of the results. These study details and disclosures come from the article preview and abstract rather than an independently checked full statistical report.

That result is useful because it comes from a controlled human comparison rather than an animal experiment or an informal report. It supports a narrow conclusion: the study did not detect a creatinine-based kidney problem under the tested conditions.

Several limitations prevent a broader safety guarantee:

1. One product was tested. The findings concern OptiMSM and cannot automatically be extended to every powder, capsule, gummy, topical preparation, or multi-ingredient formula.

2. One daily dose was tested. The study did not establish the renal safety of higher doses or determine a suitable dose for each individual.

3. Exposure lasted 16 weeks. The trial cannot answer what happens with continuous use over many months or years.

4. The participant population was limited. People with osteoarthritis and low back pain are not necessarily representative of those with chronic kidney disease, dialysis, a kidney transplant, or a recent kidney injury.

5. Kidney assessment centered on serum creatinine. The accessible report does not establish results for a comprehensive range of renal outcomes.

6. Both groups received naproxen. Giving naproxen to both groups helped balance that exposure for the MSM-versus-placebo comparison. It also means the study does not provide a clean assessment of MSM taken alone.

7. The trial was too small to exclude uncommon reactions. A rare adverse event may not appear in a study involving 100 participants.

The supplier disclosure is relevant context, but supplying the study products does not by itself invalidate the results. Conversely, a controlled design does not eliminate the need to examine the study’s methods, reporting, and limits.

The accessible preview also appears to contain statistical notation that is difficult to reconcile with the abstract’s statement that no significant difference occurred. Without independent verification of the complete analysis, the most responsible approach is to attribute the conclusion to the abstract: the authors reported no significant between-group difference. The notation should not be independently reinterpreted from the preview.

Overall, the study offers a narrow but useful safety signal. It does not resolve longer exposure, higher doses, rare injuries, different products, MSM used without naproxen, or use by people with impaired kidney function.

Why unchanged creatinine is useful but not a complete kidney-safety verdict

Serum creatinine is one laboratory measurement used when assessing kidney function. A controlled trial finding no significant creatinine difference between MSM and placebo is therefore relevant. It is not, however, a comprehensive renal safety evaluation.

The reviewed study does not establish outcomes for urine protein, urinalysis, cystatin C, electrolytes, or long-term filtration trends. MSM should not be described as improving—or as having been proven neutral for—outcomes that the accessible evidence did not adequately evaluate.

Group comparisons also cannot guarantee that every participant responded identically. Nor can a study of 100 people rule out very uncommon reactions. A limited trial can fail to detect an event that occurs rarely or emerges only after longer exposure.

Participant selection matters as well. Results from trial-selected adults with musculoskeletal conditions should not automatically be applied to people with reduced renal reserve or complex clinical circumstances. The study did not establish a renal dose adjustment, dialysis guidance, transplant guidance, or a monitoring plan for people recovering from acute kidney injury.

The best-supported wording is:

No kidney problem was detected by the reported serum-creatinine comparison during 16 weeks of MSM use.

That is different from claiming that MSM leaves the kidneys unaffected in every user.

Duration is another important gap. Short-term evidence may identify common tolerability problems while missing risks related to prolonged exposure. Arthritis UK describes MSM as generally well tolerated in short studies, with gastrointestinal discomfort the most commonly reported adverse effect, but notes that long-term adverse effects have not been studied adequately. Its patient information does not identify kidney injury as an established MSM side effect.

If your creatinine is abnormal or changes after starting a supplement, do not use this single trial to determine the cause or decide whether continued use is appropriate. A clinician who knows your medical history, laboratory results, and complete medication list is better positioned to interpret the change.

Urinary excretion, kidney exposure, and kidney injury are not the same thing

Online discussions about MSM side effects and kidneys often blur three distinct findings:

1. A substance is excreted in urine.
2. A substance is detected in kidney tissue.
3. A substance causes kidney injury.

These findings are not interchangeable.

The presence of a compound in urine provides information about elimination. By itself, it does not demonstrate that the kidneys are being damaged or “strained.” Likewise, detecting a substance in kidney tissue demonstrates exposure or distribution—not necessarily toxicity.

Evidence of kidney injury would require relevant adverse findings rather than the mere presence of a substance in an organ or its elimination in urine.

Much of the detailed information about MSM distribution and elimination comes from rats, not human kidney-safety trials. High-dose rat studies detected MSM in kidney tissue after administration and reported that substantial amounts were eliminated in urine. The reviewed pharmacokinetic evidence is predominantly animal evidence and does not establish kidney toxicity in people.

Animal doses and elimination percentages should not be converted directly into personal dosing advice. Species differences and experimental conditions make simple translation unreliable.

These findings support neither of the common extremes:

• Urinary elimination does not prove kidney damage.
• Urinary elimination does not prove that MSM cleanses, detoxifies, or benefits the kidneys.

“Detox” language is particularly misleading in this context. Excretion is a normal biological process, not evidence that a supplement removes unspecified toxins or improves renal function. The reviewed human evidence does not show that MSM cleanses the kidneys, increases filtration, or treats kidney disease.

What the animal kidney-injury experiment can—and cannot—tell us

One animal experiment is sometimes used to suggest that MSM protects the kidneys. Its design is important.

Researchers induced acute renal injury in rats using glycerol and then administered oral MSM at 400 milligrams per kilogram for six days. The experiment included three groups of six rats: a control group, a glycerol-injury group, and a glycerol-injury group treated with MSM. Compared with the glycerol-only group, the MSM-treated group had lower serum urea and creatinine and higher kidney glutathione. The authors interpreted the glutathione result as evidence of a possible antioxidant mechanism. The experiment’s design and biochemical findings are reported in the Brazilian Journal of Pharmaceutical Sciences.

This experiment may help generate research hypotheses. It does not establish that MSM protects human kidneys.

Its limitations include:

• Only six animals were included in each group.
• Kidney injury was artificially induced.
• Treatment lasted six days.
• The animal dose does not represent ordinary human supplement use.
• Changes in biochemical markers do not establish clinical benefit in people.
• The proposed antioxidant mechanism remains an interpretation rather than a demonstrated human mechanism.

This was not a toxicity study in healthy people taking an ordinary supplement. It was also not a clinical trial in people with acute kidney injury, chronic kidney disease, or another renal disorder.

The findings therefore do not show that MSM prevents, heals, or treats human kidney disease. They should not be used to justify self-treatment for a suspected or diagnosed kidney problem.

The study’s introduction mentioned possible MSM adverse effects reported elsewhere. Those statements were background material, not adverse effects produced or measured in this experiment. Presenting them as experimental findings would be inaccurate.

The appropriate interpretation is modest: MSM was associated with more favorable biochemical markers in one small, short rat model of induced injury. Whether that observation has any meaningful application to human kidney health remains unknown.

Documented MSM side effects are mostly digestive, not kidney-specific

Reported short-term side effects of oral MSM are primarily digestive:

• Upset stomach
• General gastrointestinal discomfort
• Diarrhea
• Constipation

Skin rash and allergic reactions are also listed in medical references. Poison Control describes MSM as apparently well tolerated during limited use but identifies gastrointestinal upset, rash, and allergic reactions as reported concerns. It does not list kidney injury as an established adverse effect. Poison Control nevertheless recommends consulting a physician before use and selecting products from reliable sources.

Digestive discomfort should not be treated as equivalent to a serious allergic reaction. Hives or swelling of the face, lips, tongue, or throat may indicate a serious reaction. These are allergic symptoms, not kidney effects.

The absence of kidney injury from the reviewed general side-effect lists is somewhat reassuring, but it is not definitive. Such lists may be incomplete, and limited long-term or post-market evidence may fail to reveal uncommon reactions.

Short-term tolerability also does not equal comprehensive safety. Uncertainty remains about:

• Continuous long-term use
• Rare adverse events
• People with existing kidney disease
• Pregnancy and breastfeeding
• Complex medicine combinations
• Products containing multiple active ingredients

When symptoms develop, context matters. Someone taking MSM may also be using an NSAID, a prescription medicine, another supplement, or a combination joint formula. A new symptom should not automatically be attributed to MSM, but it should not be dismissed merely because kidney injury is absent from common side-effect lists.

If symptoms begin after starting MSM, record the product name, dose, timing, complete ingredient list, and other medicines or supplements taken during the same period. Persistent or concerning symptoms warrant professional review.

Dose, duration, and product quality change how safety claims should be read

MSM dose discussions can appear contradictory. Some consumer references and scientific reviews describe doses up to 4 grams per day as generally well tolerated, while the principal creatinine study used 6 grams per day for 16 weeks.

These figures answer different questions. “Generally well tolerated” summarizes observed experience among most users in limited studies. The 6-gram trial reports what happened to selected measurements under one controlled protocol. Neither figure establishes a universally safe dose, and neither is a renal dosing recommendation.

A 2017 scientific review described MSM as generally well tolerated by most people at doses up to 4 grams daily, with relatively few known and mostly mild side effects. It also reported that one branded product had received Generally Recognized as Safe status under specified intended conditions. One author was affiliated with Bergstrom Nutrition, the manufacturer of that branded product; this is relevant context but does not automatically invalidate the review. The review’s statements concern defined evidence and uses, not every MSM product, dose, duration, or user.

The 6-gram trial should not be treated as a prescription. Its result applies to:

• One branded product
• One daily dose
• One 16-week period
• One selected participant population
• One controlled protocol
• A comparison in which both groups received naproxen

It does not establish safety beyond 16 weeks or at doses above those studied.

Product quality creates a separate uncertainty. MSM may be sold alone or combined with glucosamine, chondroitin, herbs, flavorings, or other ingredients. Medical references caution that dietary supplements are not regulated in the same way as medicines and that purity, strength, and listed ingredients may vary. Cleveland Clinic advises following package directions and discussing supplement contents with a care team.

Practical safeguards include:

• Follow the product’s labeled directions.
• Do not use a clinical-trial dose as a personal prescription.
• Avoid combining multiple MSM-containing products without calculating the total amount.
• Check the complete ingredient list rather than relying on the front-label product name.
• Prefer a product with credible independent quality verification.
• Ask a clinician or pharmacist about dose selection when medical conditions, pregnancy, nursing, prescription medicines, or multiple supplements are involved.

GRAS status also requires careful interpretation. It applies to a particular substance or product under intended conditions of use. It does not establish clinical effectiveness, provide kidney-disease dosing instructions, or guarantee that every brand, amount, duration, and user will have the same outcome.

Who should get medical or pharmacist guidance before taking MSM

Individualized guidance is appropriate when direct evidence is missing or when medical conditions and medicines make the decision more complicated.

Speak with a clinician or pharmacist before taking MSM if you have:

• Chronic kidney disease
• Reduced kidney function
• An unexplained abnormal creatinine result
• Dialysis treatment
• A kidney transplant
• A previous episode of acute kidney injury
• A complex or frequently changing medication regimen
• Pregnancy, plans to become pregnant, or current breastfeeding
• A history of serious medication or supplement allergies

The reason for caution is not that MSM has been shown to cause kidney injury in these groups. Rather, they have not been adequately studied, and the available evidence provides no validated renal dose adjustment or monitoring plan.

A medication review is particularly important if you take:

• Anticoagulants or other medicines affecting clotting, including warfarin
• NSAIDs, such as ibuprofen or naproxen
• Blood-pressure medicines
• Other herbal or natural supplements
• Multi-ingredient joint products

Medical references do not characterize every possible MSM interaction in the same way. WebMD reports potential concerns involving NSAIDs, anticoagulants, and other natural products, while Poison Control also flags blood-pressure medicines. Arthritis UK, by contrast, states that there are no well-known interactions. This variation reflects limited evidence and should not be turned into a claim that every combination is dangerous—or risk-free. Pregnancy and nursing safety are also insufficiently established. WebMD summarizes these interaction and pregnancy-related uncertainties.

The naproxen issue deserves particular attention. Both groups in the central human trial received naproxen. That design balanced naproxen exposure when comparing MSM with placebo, but it did not provide a direct comparison between MSM alone and MSM combined with an NSAID. It cannot settle the safety of every dose, duration, or MSM-and-NSAID combination used outside the trial.

Before taking MSM, give your clinician or pharmacist a complete list of:

• Prescription medicines
• Over-the-counter pain relievers
• Vitamins and minerals
• Herbs and botanical products
• Joint, protein, or recovery formulas
• Supplements used only occasionally

Include exact product names, serving sizes, and ingredient lists where possible. “Joint supplement” may not provide enough information because formulations can contain MSM alone or combine it with several other active ingredients.

The reviewed evidence does not support prescribing a reduced MSM dose, a universal testing schedule, or a stop-and-restart protocol for kidney disease. Such decisions need to be individualized rather than improvised from a study involving a different population.

Frequently asked questions

Can MSM supplements cause kidney damage?

Kidney damage has not been demonstrated in the limited evidence reviewed. The main controlled human study reported no significant creatinine difference, while general medical references primarily list digestive and allergic effects rather than kidney injury.

That does not mean kidney damage is impossible. Kidney-specific human evidence is sparse, long-term and rare risks remain uncertain, and higher-risk populations have not been adequately studied. A medically reviewed summary likewise notes that evidence about MSM’s kidney effects remains limited. WebMD reports no kidney-function change in one 16-week study while emphasizing the broader evidence gaps.

Does MSM raise creatinine?

The controlled trial discussed above did not detect a significant creatinine difference between the MSM and placebo groups under its study conditions. Both groups also received naproxen.

That result does not guarantee that creatinine will remain unchanged in every user, particularly with longer use, a different product, a higher dose, existing kidney disease, or a different medication combination. If your creatinine changes after starting a supplement, ask a qualified clinician to review the result and your complete medication and supplement list.

Is MSM safe if I have chronic kidney disease or reduced kidney function?

Safety in chronic kidney disease or reduced kidney function has not been adequately established. The principal human study does not provide validated renal dosing, dialysis guidance, transplant guidance, or evidence for people recovering from acute kidney injury.

That evidence gap is a reason for caution, not proof that MSM necessarily causes harm. Consult a clinician or pharmacist familiar with your kidney function and medications before using it.

Does MSM passing through urine mean it harms or cleanses the kidneys?

No. Urinary excretion indicates that the body eliminates at least some MSM through urine. It does not by itself demonstrate kidney injury, kidney stress, cleansing, detoxification, or therapeutic benefit.

Most of the detailed distribution and elimination evidence comes from high-dose rat research. Those findings cannot establish human kidney harm or benefit.

Can MSM be taken with NSAIDs, warfarin, or blood-pressure medication?

Do not assume these combinations are risk-free. Medical references report potential concerns involving anticoagulants such as warfarin, NSAIDs such as ibuprofen or naproxen, blood-pressure medicines, and other supplements. The probability and clinical importance of each possible interaction are not well established.

A pharmacist can assess the exact medicines, supplement formula, doses, and timing rather than relying on a general interaction list. Do not stop or change a prescribed medicine solely to start MSM without guidance from the prescriber.

The bottom line

The evidence hierarchy is straightforward:

• One short controlled human study reported no significant creatinine difference under a specific MSM regimen.
• General short-term safety reports emphasize digestive and allergic effects rather than established kidney injury.
• Animal studies of urinary elimination, tissue distribution, or induced kidney injury cannot determine human renal safety or treatment benefit.

The practical conclusion is not that MSM is proven kidney-safe. It is that no kidney-harm signal was detected under limited conditions.

People with normal kidney function should still consider dose, duration, other medicines, and product quality. Anyone with chronic kidney disease, dialysis, a kidney transplant, previous acute kidney injury, pregnancy, nursing, or a complex medication list should obtain individualized guidance from a clinician or pharmacist before using MSM.