Creatine requires a loading phase

A loading phase fills muscle creatine faster. It does not fill it fuller, and in the training trials pooled so far, gains in strength and muscle have not differed clearly between schedules. Twenty grams a day for six days and three grams a day for twenty-eight days both raised muscle total creatine about 20 percent above where it started, in the same study. What the schedule changes is how long the store takes to fill, not the level it reaches.

The store figure comes from one study, published in 1996, in 31 men, measured by muscle biopsy, and nothing since has repeated that comparison at that level of measurement. The strength and muscle evidence is broader but less direct. A 2026 analysis pooled 63 randomized trials of creatine alongside resistance training, lasting 4 to 12 weeks, and found no clear difference in strength or lean mass gains between trials that used a loading phase before a daily dose and trials that used a daily dose alone. Those comparisons are between trials rather than within them, so they show the schedules ending up in a similar place after weeks of training, not that they get there at the same speed.

The same 1996 study followed what happens afterward. Once the store was raised it stayed raised on 2 grams a day for a further 30 days. Without that continued intake it declined, and 30 days after stopping it was no different from the presupplementation level, with urinary creatinine rising over that period as the excess left the body.

Two trials cited here have compared the schedules head to head on performance. In 25 Division I football players over 10 weeks, a low daily dose and a loading protocol did not differ on squat strength, urinary creatinine or body fat, but creatine in any amount had no effect in that group, so it cannot separate two schedules being equivalent from neither one doing anything in athletes already heavily trained. In a 2024 trial, 40 young men training for 8 weeks were randomly assigned to creatine with a 5 day loading phase, the same daily creatine without loading, another form of creatine, or placebo. Both creatine monohydrate groups gained more strength and muscle than placebo, and the loading and no-loading groups did not differ from each other. With 10 people per group and no blinding reported, a small difference between the schedules could have gone undetected. A third head-to-head trial, published in 2013, randomized 27 male bodybuilders to a loading phase, a daily dose without loading, or placebo for 6 weeks and reported larger gains in several lifts in the loading group. It is not cited here because its report gives no group averages or direct loading against no-loading tests, and its dose figures differ between sections.

Starting level made a difference in one small study. In 14 adults given the same 5 days of creatine in a double-blind crossover, the vegetarians began with lower muscle creatine and took up more of it at day 1 and day 5. Creatine transporter gene expression did not differ between the groups. The study did not compare schedules.

On tolerability, an analysis of the reported side effects across 684 randomized trials, listed as industry funded and covering more than 12,800 people in creatine and placebo arms, found no consistent pattern of more side effects at higher doses or longer durations. Reported events were infrequent and mostly mild and nonspecific, and placebo arms often reported similar or greater frequencies. The sources cited here give few participant ages: the 2024 trial enrolled men aged 18 to 25, the other trials describe their participants as men, adults or football players, and the abstracts of the two pooled analyses do not state ages. The one report in a 17-year-old is the case described next. A 2025 case report describes a 17-year-old who developed acute kidney injury after a six-day high-dose loading regimen; a kidney biopsy showed cast nephropathy. A single case cannot show how often this happens or establish that creatine caused it. The US government's lactation database notes that creatine in breast milk has not been measured after supplementation, that no published information was found on effects in breastfed infants, and that creatine can raise an infant's blood creatinine, which can change estimates of the infant's kidney function.

A 2021 expert review and a 2017 society position stand both state a loading protocol directly. The review defines loading as 20 to 25 grams a day for 5 to 7 days, or 0.3 grams per kilogram of body mass a day, followed by 3 to 5 grams a day to maintain the store, and names the same 1996 study behind this claim for that comparison. The position stand recommends the same figures, about 0.3 grams per kilogram a day for 5 to 7 days, as the quickest way to raise the store, followed by a 3 to 5 gram maintenance dose. Both also come from overlapping groups of authors, and the position stand lists a supplement industry trade association in its funding, so the two are closer to one reading than to two.