Is creatine bad for your kidneys?

In healthy people taking standard doses, randomized trials have not found kidney harm. A 2026 meta-analysis of 20 randomized trials found creatine raised blood creatinine slightly, by about 0.13 mg/dL, but did not change urea or estimated kidney filtration rate. That creatinine bump can make a routine kidney test look worse than it is, so tell your doctor you take creatine. People with existing kidney disease should not take it without medical advice.

Does creatine cause hair loss?

The concern traces to a single 2009 study in rugby players that reported a rise in DHT and measured no hair. A 2025 randomized trial in 45 resistance-trained men found that 5 grams a day for 12 weeks did not change DHT, the DHT-to-testosterone ratio, or measures of hair density and thickness.

Do you need to do a creatine loading phase?

No. Loading (about 20 grams a day split into four doses for 5 to 7 days) fills muscle creatine stores in about a week. Taking about 3 grams a day without loading reaches a similar level in roughly four weeks, with less early weight gain and less chance of stomach upset.

Does creatine make you gain weight?

Usually a little at first. Weight gain is the most consistently reported side effect, roughly 1 to 2 kilograms (about 2 to 4 pounds) during a loading week, mostly water drawn into muscle. Over longer training periods, the added weight is mostly lean tissue, and creatine does not increase body fat.

📅 Originally published October 12, 2024 · Updated October 2026 ✍️ Josh ⏱️ 5 min read

Creatine: Benefits, Side Effects, and a Balanced Look at the Evidence

Creatine is one of the most extensively researched and popular supplements in sports and fitness. Known for improving muscle mass, strength, and high-intensity performance, it has become a staple for athletes, lifters, and everyday exercisers. Beyond the gym, researchers are studying creatine for brain function and healthy aging, where the evidence is newer and more mixed. This post covers the benefits, the open questions, and the side effects, so you can make an informed decision.

What Is Creatine?

Creatine is a naturally occurring compound your body makes, mainly in the liver and kidneys, from amino acids, and also gets from red meat and fish. About 95% of it is stored in muscle. It's stored largely as phosphocreatine, which rapidly regenerates adenosine triphosphate (ATP), the primary energy carrier in cells. On a typical diet, muscle stores are only 60–80% full; supplementing raises them by roughly 20–40%, increasing your capacity for short, intense efforts. People who eat little meat start lower and tend to gain more.

Benefits of Creatine Supplementation

1. Muscle Mass and Strength

Improved performance: Combined with resistance training, creatine consistently increases strength, power, and muscle mass more than training alone.
Mechanism: More phosphocreatine means faster ATP regeneration during intense exercise, so you can do a bit more work per session, and that adds up over weeks.
Research evidence: The International Society of Sports Nutrition (ISSN) puts typical gains in high-intensity and repeated-effort performance at roughly 10–20% after loading. Responses vary, and people whose stores are already high may notice little.

2. Muscle Recovery

Muscle damage: Some studies suggest creatine reduces markers of muscle damage and inflammation after hard exercise, though results are mixed.
Training tolerance: Studies in athletes found no increase, and sometimes a decrease, in cramping and injuries among creatine users.

3. Brain Function

Memory: The brain uses creatine for energy too. A 2024 meta-analysis of 16 trials found a modest improvement in memory, but not in overall cognition or executive function. Who benefits most is unsettled; vegetarians and people under stress may respond more, and in a 2024 lab study a single large dose partly offset the cognitive slump of a sleepless night.
Neurological disease: Early optimism has had to be revised. The largest trial, in more than 1,700 people with early Parkinson's disease, was stopped early because 10 grams a day wasn't slowing the disease. A small 2025 Alzheimer's pilot found higher brain creatine and better scores on some cognitive tests after eight weeks, but it had no placebo group.

4. Benefits for Aging Adults

Muscle preservation: Creatine helps counter age-related muscle loss (sarcopenia) when combined with resistance training. A meta-analysis of 22 trials in older adults found about 1.4 kg more lean mass and greater strength than training alone.
Bone health: The hope that creatine would protect bone hasn't held up. A two-year trial in 237 postmenopausal women found no improvement in bone mineral density, though some measures of hip bone geometry were better preserved, and a 2026 meta-analysis also found no change in bone density.
Cognitive aging: No trial has yet shown that creatine prevents or slows age-related cognitive decline.

5. High-Intensity Exercise Performance

Sports performance: Sprinting, weightlifting, team sports with repeated sprints, and interval training benefit most.
Versatility: It helps across many kinds of short, intense activity; effects on pure endurance are smaller and less consistent.

6. Safe and Well-Researched

Extensive studies: Creatine monohydrate is among the most studied supplements, and the ISSN concludes it is safe for healthy people at recommended doses, in studies lasting up to five years.
Regulatory status: The FDA doesn't approve supplements, but it raised no questions about a notice that creatine monohydrate is "generally recognized as safe" as a food ingredient, and European regulators accept that 3 grams a day improves performance in repeated bursts of high-intensity exercise.

Potential Side Effects and Considerations

1. Temporary Weight Gain

Water retention: Weight gain is the most consistently reported side effect, typically about 1–2 kg (2–4 pounds) during a loading week as muscles take on water.
Not fat gain: The early gain is water; later gains with training are mostly muscle.

2. Digestive Issues

Stomach upset: Some people get cramps, nausea, or diarrhea, mostly with large single doses. In one trial, diarrhea was far more common with a single 10-gram dose than with two 5-gram doses.
Mitigation: Take it with meals, dissolve it fully, and split larger doses.

3. Kidney and Liver Health

Research insights: A 2026 meta-analysis of 20 randomized trials found creatine raised blood creatinine slightly without changing other measures of kidney function. Trials longer than a year are still needed, and liver data are reassuring but thinner.
The lab-test catch: Because standard kidney tests use creatinine, creatine can make your kidney function look worse than it is. Tell your doctor you take it.
Existing conditions: If you have kidney or liver disease, talk to your doctor before starting.

4. Dehydration and Cramping

Mostly a myth: Studies in athletes, including in the heat, found no increase in cramping or dehydration. Staying hydrated is still good practice.

5. Potential Interactions

Medications: Few direct interactions are known, but be cautious with drugs that can strain the kidneys, such as regular high-dose NSAIDs, and check with your doctor if you take prescription drugs.
Hair loss: This worry traces to one 2009 study that found a rise in the hormone DHT and didn't measure hair. A 2025 randomized trial found no change in DHT or hair.

6. Quality of Supplements

Purity matters: Choose plain creatine monohydrate, verified by a third-party tester such as NSF Certified for Sport or Informed Sport. Be wary of gummies: in 2024 testing by NOW Foods, 5 of 12 gummy products contained little to no creatine.

Best Practices for Creatine Supplementation

Use research-based dosing: Studies typically use a loading phase of about 20 grams a day (in four doses) for 5–7 days, then 3–5 grams a day, or simply 3–5 grams a day, which fills muscle stores in about three to four weeks.
Stay hydrated: Drink water throughout the day.
Monitor your response: Adjust timing or dose if your stomach complains.
Consult professionals: Especially if you have a health condition, take medications, or are pregnant.
Combine with training: Creatine amplifies a structured resistance program; it doesn't replace one.

This article is for educational purposes only and isn't medical advice. Talk to your doctor before starting any new supplement or exercise program, especially if you have kidney or liver disease, diabetes, or high blood pressure, take prescription medication, or are pregnant or breastfeeding. Teenagers should check with a pediatrician first.

Key Sources

Kreider RB, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition, 2017;14:18. PubMed
Antonio J, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition, 2021. PubMed
Antonio J, et al. Part II. Common questions and misconceptions about creatine supplementation. Journal of the International Society of Sports Nutrition, 2025. PubMed
Tsiaras A, et al. The effect of creatine supplementation on kidney function: a systematic review and meta-analysis of randomized controlled trials. Journal of Renal Nutrition, 2026. PubMed
Chilibeck PD, et al. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. Open Access Journal of Sports Medicine, 2017. PubMed
Chilibeck PD, et al. A 2-yr randomized controlled trial on creatine supplementation during exercise for postmenopausal bone health. Medicine & Science in Sports & Exercise, 2023. PubMed
Smith-Ryan AE, et al. Creatine supplementation in women's health: a lifespan perspective. Nutrients, 2021. PubMed
Xu C, et al. The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis. Frontiers in Nutrition, 2024. PubMed
NINDS NET-PD Investigators (Kieburtz K, et al.). Effect of creatine monohydrate on clinical progression in patients with Parkinson disease: a randomized clinical trial. JAMA, 2015. PubMed
Lak M, et al. Does creatine cause hair loss? A 12-week randomized controlled trial. Journal of the International Society of Sports Nutrition, 2025. PubMed