What creatine is and how it works
Your liver and kidneys make about 1 gram of creatine a day from three amino acids (glycine, arginine and methionine), and you get more from meat and fish. Almost all of it is stored in your muscles, where it helps refill ATP, the fuel used in the first seconds of an intense effort.
Supplements raise those muscle stores above what food alone provides. Creatine monohydrate is the most widely used and studied form. NIH notes that other, usually more expensive forms, such as creatine ethyl ester or buffered creatine, have not been shown to work better or be safer.
What the evidence shows
| Possible benefit | Strength of evidence | What studies show |
|---|---|---|
| Strength and power in short, intense efforts | Strong | Better results in lifting, sprinting and repeated all-out sets in many trials |
| Muscle and strength gains with training | Strong in younger adults; good in older adults who also lift | Creatine alone, without resistance training, gives older adults little extra muscle |
| Endurance sports | Little benefit | Long aerobic efforts don't rely on this energy system, and water weight may slow you down |
| Memory | Emerging (moderate certainty) | A 2024 review of 16 small trials found a modest improvement in memory |
| Overall thinking and focus | Low to very low certainty | No clear effect on overall cognition or executive function |
The 2024 brain review included 492 adults, mostly healthy, and few people over 60. Its authors call for larger trials before firm conclusions. Creatine is not a substitute for care if you have memory problems.
Side effects and water weight
NIH says studies have found no consistent set of side effects apart from weight gain. People starting creatine with a strength program often gain about 1 to 2 kg (2 to 4 pounds) in the first month, mostly from extra water in muscle. Longer training studies often show no lasting rise in total body water.
- Stomach upset. Large single servings, above about 10 grams, can cause diarrhea. Smaller servings spread through the day are easier on the gut.
- Cramps and dehydration. These are reported anecdotally, but a 2021 expert review concluded creatine does not cause dehydration or muscle cramping. Drinking enough water is still sensible.
- Hair loss. The concern comes from one small study of rugby players that found a rise in DHT, a hormone linked to hair loss. It has not been repeated, and most evidence does not support a link.
- Mood. Cleveland Clinic notes creatine may raise the risk of mania in people with bipolar disorder.
Safety hasn't been well studied in pregnancy, breastfeeding, diabetes, or kidney or liver disease. Some studies in teens found no harm, but ask a pediatrician before a child or teen takes it.
Is creatine bad for your kidneys?
In healthy people, more than 20 years of research has found no kidney harm from recommended amounts. Reported cases of kidney trouble involved existing kidney disease, other medicines or supplements, steroid use, or very large doses.
There is one catch for lab results. Your body breaks creatine down into creatinine, the marker labs use to estimate kidney function. Taking creatine, or eating a lot of meat, can raise blood creatinine and make your eGFR look lower even when your kidneys are fine. Tell your clinician you take creatine before a creatinine test.
If you have kidney disease, take medicines that affect the kidneys, or have had a low eGFR, talk with your clinician before taking creatine.
How people usually take it
NIH and sports nutrition reviews describe two common approaches. One is about 3 to 5 grams a day, which fills muscle stores in about 4 weeks. The other starts with a short, higher-dose loading week to fill stores faster, then drops to the daily amount. Loading is optional; both end up at similar muscle levels.
Timing around a workout matters less than taking it every day. See when to take creatine for before versus after, rest days and food. Some pre-workout products also contain creatine, so check labels if you use both.
Common questions
Does creatine cause water retention?
It can at first. Many people gain about 2 to 4 pounds in the first weeks, mostly water in muscle, and longer studies often show no lasting rise in total body water.
Is creatine bad for your kidneys?
In healthy people, research at recommended amounts has not found kidney harm. It can raise blood creatinine on a lab test, so tell your clinician you take it. If you have kidney disease, ask first.
Does creatine cause hair loss?
Most evidence does not support a link. The concern comes from one small study that found a rise in the hormone DHT, and that result has not been repeated.
Do you need to load creatine?
No. A loading week fills muscle stores faster, but taking about 3 to 5 grams a day reaches similar levels in about 4 weeks.
Is creatine good for women and older adults?
Studies in women, including after menopause, show strength benefits, mostly when creatine is paired with resistance training. Older adults also gain the most when they lift. Creatine without exercise does little for muscle in older adults.
Which type of creatine is best?
Creatine monohydrate. It is the most studied form, and other forms have not been shown to work better or be safer.
Sources
- Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals (Creatine) NIH Office of Dietary Supplements
- Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? (Antonio et al., 2021) Journal of the International Society of Sports Nutrition
- The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis (Xu et al., 2024) Frontiers in Nutrition
- Creatine Cleveland Clinic
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.