Supplements
Creatine: Benefits, Side Effects and What to Check First
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed August 20267 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
QUICK ANSWER
Creatine monohydrate is one of the best-studied supplements there is. Trials report gains of 10 to 20 percent in short, hard efforts, and no evidence of kidney harm in healthy adults. The real catch is a measurement one. Creatine raises blood creatinine, so a routine kidney result can read falsely high.
See which markers to check before you start →Creatine has left the gym. It now turns up in menopause podcasts, brain-health threads and the supplement drawer of people who have never touched a barbell.
With that reach has come a familiar worry. Is it doing something to my kidneys? The short answer is no. The longer answer is more useful, because creatine does change one blood number, and knowing which one saves a lot of panic.
As of August 2026. Sources are the International Society of Sports Nutrition position stand, a 2023 narrative review in Nutrients, and NHS guidance. Every figure below is cited and linked.
1. Does creatine actually do anything?
Yes, and the effect is narrow rather than magical. Your body already makes creatine, and you get more of it from meat and fish. A supplement simply fills the muscle stores closer to the top.
Fuller stores mean your muscles can repeat a hard effort sooner. The International Society of Sports Nutrition puts numbers on it in its position stand.
“After creatine loading, performance of high intensity and/or repetitive exercise is generally increased by 10–20%.”
— ISSN position stand, Journal of the International Society of Sports Nutrition, 2017
The same review reports larger strength gains during rehabilitation after injury, and better outcomes in older adults who lift. What it does not show is a benefit for steady endurance work. If your training is all long runs, creatine has little to offer.
2. What are the real side effects?
Most of the reputation is folklore. Two effects are genuine, and both are mild.
- Water weight. Creatine pulls water into muscle, so the scale often moves 1 to 2 kg in the first week.
- Gut upset. This tends to follow one large dose. Splitting it across the day usually settles it.
- Hair loss. Traced to a single small 2009 study. A 2025 randomised trial found no effect on DHT.
- Testosterone. Creatine does not raise it. The testosterone guide covers where that myth began.
Cramping and dehydration are the other two claims people repeat. The ISSN position stand states there is no evidence in the peer-reviewed literature that creatine increases the reported rate of musculoskeletal injury, dehydration, cramping or gut upset.
3. Is creatine safe for your kidneys?
In healthy adults, the evidence is reassuring and it is not thin. The ISSN position stand concludes that short and long-term supplementation, up to 30 g a day for five years, is safe and well tolerated in healthy people.
A 2023 narrative review in Nutrients went further. Its title asks whether it is time for a requiem for creatine-induced kidney failure. The authors report that randomised controlled trials do not support the idea in people with normal kidney function.
The caveat is real, though. That same review advises caution where kidney disease already exists. If you have known kidney problems, or take medicines that affect the kidney, ask a qualified clinician before you start.
4. Why does your blood test read high on creatine?
Here is the part almost nobody is told. Your body breaks creatine down into creatinine, a waste product the kidneys clear. Take more creatine and you make more creatinine.
Creatinine is exactly what a kidney blood test measures. Your eGFR, the headline kidney number, is then calculated from it. So a higher creatinine drags the eGFR down, and healthy kidneys can be flagged as struggling. The NHS says so plainly.
“Taking this supplement can make it look as though you have higher levels of creatine in your body and that your kidneys are not functioning normally.”
— NHS, taking PrEP with other medicines and supplements
The fix costs nothing. Tell whoever reads your result that you take creatine. Our creatine and creatinine guide covers how big the shift usually is, and the creatinine blood test guide explains the ranges themselves.
5. What should you check before you start?
A baseline before your first loading week is the single most useful thing you can do. It gives every later result something to be compared against.
- Creatinine and eGFR. The two numbers creatine shifts. Measure them clean, before you start.
- Urea. A second kidney marker that creatine does not push in the same way.
- ALT, ALP and albumin. Liver and protein markers, useful if you are stacking other supplements too.
- TSH, free T4 and free T3. Thyroid drives the fatigue and brain fog people often ask creatine to fix.
All of those sit in Thyroid & Vital Organs (£159, 16 markers), a home finger-prick kit read by a UKAS-accredited UK laboratory. The kidney function test guide explains what each marker is doing.
One reassurance while you are here. Creatine does not meaningfully move your red cells, white cells or platelets, so a full blood count reads the same whether you take it or not.
6. How much creatine, and when?
The position stand describes two routes to the same place.
- Load, then maintain. Roughly 5 g four times a day for 5 to 7 days, then 3 to 5 g a day.
- Go slow. Or take 3 g a day for 28 days and reach full stores without the loading week.
- Pick monohydrate. It is the cheapest form and the one nearly every trial used.
Timing barely matters. Consistency does, because the benefit comes from keeping the stores full rather than from any single dose. If you stop, they drift back down over about four to six weeks, which the stopping creatine guide walks through.
7. What about creatine beyond the gym?
This is where the noise is loudest and the evidence is youngest. The brain uses creatine too, which is why researchers keep testing it on mood, fog and sleep loss.
We have covered each strand separately and honestly, including the trials that found nothing: brain fog, mood, women over 40 and women over 50.
One thought before you spend. Tiredness and fog have common, testable causes: low iron, low B12, low vitamin D, an underactive thyroid. The energy and fatigue hub gathers those. It is worth ruling them out before a supplement gets the credit or the blame.
READY TO TEST?
Measure it, then decide
Thyroid & Vital Organs covers creatinine, eGFR, urea, liver markers and full thyroid function in one home finger-prick kit. Results are read by a UKAS-accredited UK laboratory and reviewed by a qualified clinician, with every marker set against its optimal range rather than the clinical minimum.
Frequently asked questions
Is creatine safe to take every day?
For healthy adults the evidence says yes. The ISSN position stand reports that supplementation up to 30 g a day for five years is safe and well tolerated. Ask a clinician first if you have known kidney disease.
Does creatine cause bloating?
It can pull water into muscle, so the scale often moves 1 to 2 kg early on. Gut discomfort usually follows one large dose rather than creatine itself, and splitting the dose across the day tends to settle it.
Does creatine cause hair loss?
The claim traces back to one small 2009 study of rugby players. A 2025 randomised trial measured DHT directly and found no effect. Our hair loss guide sets out both in full.
Does creatine affect blood test results?
One marker, mainly. Your body turns creatine into creatinine, so blood creatinine rises and the calculated eGFR can look lower. The NHS notes this can make kidneys look as though they are not working normally. Tell whoever reads your result.
Should you stop creatine before a blood test?
You do not have to, and it is usually better to be honest about taking it than to pause. If you want the cleanest kidney reading, leaving four weeks between your last dose and the test lets stores return to baseline.
Is creatine worth taking for women?
The strength evidence applies to women as it does to men. The newer work on mood, fog and the menopause transition is early and mixed, so treat the headlines carefully. Our guides for women over 40 and over 50 go through the trials.
Related guides
Does Creatine Raise Creatinine?
How far it shifts the number, and how to read a high result.
Does Creatine Cause Hair Loss?
The 2009 rugby study, and what the 2025 trial found.
Does Creatine Increase Testosterone?
Where the myth came from, and how to measure yours.
What Happens When You Stop Creatine
Water weight, muscle stores and the cleanest test window.
Creatine for Women Over 40
The menopause-brain research, and what to test first.
Kidney Function Test
What creatinine, eGFR and urea are each telling you.
Test for this
Keep reading