Does caffeine counteract creatine?

Supplementation with either creatine or caffeine has consistently been shown to enhance high-intensity exercise performance in most people, and the ingredients are thought to achieve this feat via separate physiological mechanisms. There also doesn’t appear to be any pharmacokinetic interactions when caffeine or creatine are taken together; i.e., neither caffeine nor creatine affects the other’s blood levels.^[1] Caffeine does not influence creatine’s ability to increase muscle phosphocreatine storage^[2], which makes combined supplementation of creatine and caffeine an attractive prospect for athletes and recreational exercisers alike.

However, there is some evidence to suggest that chronic caffeine consumption during creatine loading blunts the ergogenic (i.e., performance-enhancing) effect of creatine.^[3] One notable study found that six days of creatine loading increased the amount of torque produced by the quadriceps during a resistance exercise protocol but adding a single dose of 5 mg of caffeine per kg of body weight during the final three days of the six-day creatine-loading protocol produced no improvement in exercise performance.^[2]

If caffeine does interfere with creatine’s ergogenic effect, it may be a consequence of these supplements having opposing effects on muscle relaxation time. Creatine increases calcium reuptake into the sarcoplasmic reticulum (a structure in muscle cells that stores calcium) and reduces muscle relaxation time, whereas caffeine increases calcium release from the sarcoplasmic reticulum and increases muscle relaxation time.^[4] Theoretically, reduced muscle relaxation time would be conducive to generating high amounts of force quickly and in rapid succession.

Caffeine may also blunt the ergogenic effect of creatine because co-ingestion of these ingredients has been reported to cause gastrointestinal distress in some people.^[3][5]

While these data are thought-provoking, it’s far from clear whether caffeine and creatine should be consumed separately to maximize their ergogenic effects. For instance, despite caffeine potentially diminishing creatine’s ergogenic effect when ingested during creatine loading, other studies found that after five to six days of creatine loading, supplementation with caffeine before an exercise test enhanced performance.^[6][7]

Additionally, studies that investigated the acute and chronic effects of supplementation with a multi-ingredient preworkout supplement containing both caffeine and creatine reported enhanced exercise performance and muscular adaptations.^{[8][9][10][11]} However, these preworkout supplements also contained ergogenic ingredients other than creatine and caffeine (e.g., beta-alanine), which may have confounded the results.

Lastly, and most recently, the results from two studies cast further uncertainty on whether one should refrain from co-ingestion of caffeine and creatine. In the first study, a 2016 randomized controlled trial, 54 physically active men supplemented with a daily loading dose of creatine, creatine plus 300 mg caffeine anhydrous (equivalent to about 3 cups of coffee), creatine plus coffee (containing 300 mg of caffeine), or placebo for five days. No differences between groups were found for changes in upper- or lower-body strength, upper- or lower-body muscular endurance, or repeated sprint performance.^[5] This dose of caffeine didn’t appear to blunt creatine’s effects in this study, but creatine also didn’t appear to have any positive effects to blunt.

In the second study, a small controlled trial published in 2022, 28 resistance-trained adults were randomly assigned to supplement with a non-loading dose of creatine monohydrate (0.1 grams per kg of body weight), caffeine (3 mg per kg of body weight), creatine plus caffeine, or placebo for four to five days per week before performing resistance exercise. After six weeks of training, there were no differences between groups for changes in upper- or lower-body strength, upper- or lower-body muscular endurance, or fat-free mass; however, the group that supplemented with creatine alone, and only that group, experienced an increase in quadriceps muscle thickness compared to baseline.^[12] In this study, the creatine group did see positive effects (albeit in muscle thickness, not performance) that the caffeine + creatine group did not. However, the study was significantly underpowered, limiting its ability to detect small changes over time. The intermittent (as opposed to daily) supplementation protocol may have also influenced the results.

The evidence indicating that co-ingestion of caffeine and creatine blunts creatine’s ergogenic effect is weak, and is seen mainly in studies that implemented a creatine loading protocol, implying that this effect — if it exists at all — may not be relevant when creatine loading is not used. Nonetheless, this level of evidence may be sufficient to lead some people to reconsider their current supplementation practices.

In terms of practical recommendations to mitigate the potentially unfavorable interaction between caffeine and creatine, one option is to supplement caffeine before exercise and creatine after exercise.^[13] If co-ingesting caffeine and creatine, it may be prudent to stick to a lower dose of caffeine (≤ 3 mg per kg of body weight), as the studies that reported a negative interaction had participants supplement with 5 mg per kg of body weight. Additionally, early studies on creatine supplementation, which had participants mix creatine with hot coffee or tea, didn’t find that these beverages inhibited creatine’s ergogenic effect;^[14][15] typical cups of coffee and tea contain far less than 5 mg/kg of caffeine. Further, coffee and tea are not simply “caffeine water” and contain hundreds of other bioactive compounds, which could have influenced the results.