Creatine Side Effects for Women: Kidneys, Hair, Periods and the Pill

The women-only creatine trials record no side effect specific to women: across the 29 studies that monitored side effects in women, 951 women in all, there were no deaths or serious adverse outcomes, and gut upset, weight and kidney and liver readings did not differ significantly from placebo.¹ Expect a small rise in the creatinine blood reading, extra water held inside muscle and, with large single servings, an upset stomach. No trial has settled the questions women ask most: none has measured oestrogen or testosterone as an outcome in women taking creatine, tested whether creatine changes how the pill works, or recruited women with PCOS. What it does is on the Wellgard creatine guide.

Evidence at a glance

• Trials: 29 studies that monitored adverse outcomes in women, 951 women, pooled in 2020; two cycle-phase loading trials of 30 and 39 women.
• Longest trials: seven postmenopausal trials, 608 women, 12 to 104 weeks, pooled in 2026.
• Strongest measured outcome: total adverse events in women, risk ratio 1.24 (0.51 to 2.98), not significant.
• Not tested: a woman's own hormones as an outcome, creatine with the pill, women with PCOS, hair in women, pregnancy, breastfeeding.

Sources checked on 14 October 2026.

Is creatine safe for women? What 29 trials of 951 women recorded

In the 2020 pooled analysis, 29 studies monitored adverse outcomes in 951 women, and "There were no deaths or serious adverse outcomes reported." Total adverse events (risk ratio 1.24, confidence interval 0.51 to 2.98), gut events (1.09, 0.53 to 2.24) and weight gain (about 1.2 to 1.4 kg, not significant) did not differ from placebo, and "No statistically significant difference was reported in measures of renal or hepatic function."¹ In the 2026 pooling of seven postmenopausal trials, 608 women, "Adverse events were mild and similar to placebo; renal indices were unchanged."²

The 2020 authors ask future women's trials to report adverse outcomes comprehensively;¹ a count of 951 women says nothing about kidney disease, pregnancy or a medicine you take.

Does creatine affect a woman's kidneys? The creatinine blood reading

Creatine breaks down into creatinine, the waste product a kidney blood test measures, so taking creatine raises the reading without changing what the kidneys do. Across 12 pooled trials (177 people on creatine, 263 controls) serum creatinine rose a little, most clearly in the first week, while the filtration rate did not differ from controls; the authors call it "metabolic turnover rather than renal impairment".³ In a five-day loading trial of 15 women and 15 men, blood pressure, plasma creatinine and estimated creatinine clearance did not change.⁴ The NHS says it on the one page that names creatine: the supplement "can affect the results of your kidney function tests", so "If you're using creatine, let your clinic doctor know".⁵ The words for the GP are on creatine vs creatinine.

Does creatine cause water weight or bloating in women?

Water, yes; bloating, only from large single servings. In 30 active women who loaded 20 g a day for five days, body mass did not differ from placebo across the cycle, while total body water rose by about 0.8 litres after loading in the high-hormone (luteal) phase (supplier-donated creatine).⁶ The pooled women's weight difference of about 1.2 kg was not significant.¹ Stomach upset tracks serving size; the trial figures are on does creatine cause bloating, the scale on does creatine make you gain weight.

Does creatine cause hair loss in women?

No trial has measured hair in women; the worry came from men. It traces to a 2009 crossover study of 20 male rugby players in which DHT, a hormone, rose after a 25 g a day loading week; hair was not measured.⁷ The only trial to measure hair directly, 45 men on 5 g a day for 12 weeks by supplier-linked authors, found no difference from placebo in DHT, testosterone, hair density or hair thickness.⁸ Shedding is on does creatine cause hair loss.

Does creatine affect your period, the pill or PCOS?

Periods: two small five-day loading trials followed active women across the menstrual cycle, 30 women for body water and 39 for recovery and repeated sprints, both with supplier-donated creatine and one supplier-linked author.^{6, 9} Neither reported any change in cycle length or bleeding, and neither set out to measure them. In the 39-woman trial sprint performance and recovery dipped in the high-hormone phase in both groups; fatigue index improved more on creatine in that phase (interaction p = 0.048), while the authors call the wider suggestion that creatine offsets the dip not statistically significant.⁹ No creatine trial we found measured period pain.

The pill: no trial has tested whether creatine changes how any contraceptive works, so there is no interaction to report and none ruled out. The 30-woman trial included women on hormonal contraception and found no significant difference from naturally menstruating women in body water or body mass, the only pill-related measurement we found; it used salivary oestrogen only to confirm cycle phase, so no trial has measured a woman's hormones as an outcome on creatine.⁶ HRT is in the same position, on creatine in perimenopause and menopause.

PCOS: no trial has recruited women with the condition, so nothing is known either way. The NHS now calls it polyendocrine metabolic ovarian syndrome (PMOS), "a hormone condition that can affect hair growth, periods, fertility and mood", and says to see a GP if you think you might have it.¹⁰ The supplements that have been tested in PCOS are on which PCOS supplements have evidence.

Can you take creatine while pregnant, trying to conceive or breastfeeding?

Ask your midwife or GP first: the Cochrane review found no randomised trial of creatine in pregnant women,¹¹ and the search behind creatine while pregnant or breastfeeding found no study of any kind in breastfeeding women.

Who should check with a GP or pharmacist first?

• Kidney disease or a reduced eGFR: the trials are in healthy kidneys. The NHS says people on long-term medicines that can affect the kidneys, such as lithium, omeprazole or non-steroidal anti-inflammatory drugs, should be tested regularly, and creatine moves that reading.¹²
• A prescribed medicine, including the pill or HRT: no interaction has been studied; tell your doctor or pharmacist what you take, as the NHS asks for any supplement.⁵
• Pregnancy, trying to conceive or breastfeeding: no trial, so the midwife or GP decides.¹¹
• Under 18: see is creatine safe for teenagers.
• High blood pressure, diabetes, a thyroid condition or any condition under treatment: blood pressure did not change in the five-day trial above, and no trial on this page tested those conditions, so ask your doctor.⁴

The full list is on creatine side effects.

What we don't know

• No trial has measured oestrogen or testosterone as an outcome in women taking creatine.
• No trial has tested creatine with any contraceptive or HRT, or recorded cycle length, bleeding or period pain as an outcome.
• No trial has recruited women with PCOS or high blood pressure; the kidney evidence is from healthy kidneys.
• No trial has measured hair in women; both hair-related trials are in men.

Frequently asked questions

What are the pros and cons of creatine for females?

The pros, with the trials behind them, are on creatine for women. The cons: a creatinine reading to explain to the GP, water held inside muscle and stomach upset from large servings. Across 951 women, no serious adverse outcome.¹

Does creatine affect female hormones?

Not measured as an outcome, which is different from no effect. No trial has measured oestrogen or testosterone as an outcome in women taking creatine; the largest hormone trial, 45 men over 12 weeks, found no difference from placebo in testosterone or DHT.⁸

Can creatine affect your period or make cramps worse?

Neither cycle trial reported a change in cycle length or bleeding, and no creatine trial has measured period pain.^{6, 9} A period that changes markedly is a GP question whatever you take.

Can women with thyroid problems take creatine?

No creatine trial we found recruited women with a thyroid condition or reported a thyroid outcome. A treated condition is the GP's call; mention the creatinine reading on routine bloods.⁵

Sources

1. de Guingand DL, et al. Risk of adverse outcomes in females taking oral creatine monohydrate: a systematic review and meta-analysis. Nutrients, 2020. Pooled analysis, 29 studies, 951 women; no external funding, no conflicts declared. PubMed 32549301.
2. Naddafha S, et al. Creatine monohydrate for lean mass, strength, and bone density in postmenopausal women: a systematic review and meta-analysis. Journal of the International Society of Sports Nutrition, 2026. Pooled analysis, 7 trials, 608 women; one author chairs an advisory board supported by a creatine maker; society funding from creatine makers on occasion. PubMed 42141930.
3. Naeini EK, et al. Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrology, 2025. Pooled analysis, 12 trials, 440 people; no competing interests declared. PubMed 41199218.
4. Mihic S, et al. Acute creatine loading increases fat-free mass, but does not affect blood pressure, plasma creatinine, or CK activity in men and women. Medicine and Science in Sports and Exercise, 2000. Randomised trial, 15 women and 15 men, 5 days; non-US government support. PubMed 10694109.
5. NHS. Taking PrEP with other medicines and herbal supplements. Page last reviewed 10 March 2023 (review overdue). nhs.uk.
6. Moore SR, et al. A randomized controlled trial of changes in fluid distribution across menstrual phases with creatine supplementation. Nutrients, 2023. Randomised trial, 30 women, 5-day loading in two cycle phases; no external funding, supplier-donated creatine, one supplier-linked author. PubMed 36678300.
7. van der Merwe J, et al. Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clinical Journal of Sport Medicine, 2009. Randomised crossover trial, 20 men, 21 days; funding not checked. PubMed 19741313.
8. Lak M, et al. Does creatine cause hair loss? A 12-week randomized controlled trial. Journal of the International Society of Sports Nutrition, 2025. Randomised trial, 45 men (38 completed), 12 weeks; supplier-linked authors. PubMed 40265319.
9. Gordon AN, et al. The effects of creatine monohydrate loading on exercise recovery in active women throughout the menstrual cycle. Nutrients, 2023. Randomised crossover trial, 39 women, 5-day loading; no external funding, supplier-donated creatine, one supplier-linked author. PubMed 37630756.
10. NHS. Polyendocrine metabolic ovarian syndrome (PMOS). Page last reviewed 30 June 2026. nhs.uk.
11. Dickinson H, et al. Creatine for women in pregnancy for neuroprotection of the fetus. Cochrane Database of Systematic Reviews, 2014. Systematic review; no randomised trial found. PubMed 25523279.
12. NHS. Chronic kidney disease: diagnosis. Page last reviewed 22 March 2023 (review overdue). nhs.uk.

Spotted something out of date? Email support@wellgard.co.uk with the page address and the sentence.

This article is general information, not medical advice. If you are pregnant, breastfeeding, have a kidney condition or take regular medication, ask your GP or pharmacist before starting creatine.