Creatine and coffee: does caffeine cancel creatine?

Does morning coffee cancel out your creatine? Probably not. Caffeine taken before a workout, after a creatine loading phase, does not inhibit creatine in any way and sometimes adds a little boost. The doubt only concerns caffeine taken every day during the loading phase, and it is based on a handful of small, conflicting studies. Here is what seventeen studies measure.

Where does the rumour come from?

It all starts with a 1996 trial on nine men. Six days of creatine loading (0.5 g per kilo per day) increased muscle phosphocreatine by 4 to 6% and machine-measured strength by 10 to 23%. With an additional 5 mg of caffeine per kilo per day, phosphocreatine increased just as much, but the strength gain disappeared completely. The authors conclude that caffeine counteracts the effect of creatine loading.

The result spread across gyms. But it is a single small trial, with a high dose of creatine and daily caffeine. A 2015 review speaks of "conflicting evidence": some studies support this, others do not.

Two very different ways to combine them

The two systematic reviews on the subject make the same distinction, and it changes everything. The 2023 review, covering 10 studies, separates caffeine taken once before exercise, after loading (5 to 7 mg per kilo, after 5 to 6 days of 0.3 g of creatine per kilo per day) from caffeine taken every day during loading. In the first case, caffeine adds a benefit to creatine alone in 3 out of 5 studies. In the second, in only 1 out of 5 studies.

The 2022 review, also covering 10 studies, reaches the same split. Three studies find that creatine loading does not decrease the effect of caffeine taken before exercise. When both are taken daily together, two studies see caffeine inhibit creatine, three see no interaction, and one even finds a synergy. Its conclusion: creatine loading does not harm the effect of caffeine, but caffeine taken every day during loading might reduce the effect of creatine.

Caffeine before exercise, after loading: it works

In 14 trained men, after 6 days of loading (0.3 g per kilo per day) and a caffeine washout, 5 mg of caffeine per kilo one hour before an exhaustion run kept them going for 222 seconds compared to 198 with a placebo, with a lower perceived effort. In 12 active men, caffeine (6 mg per kilo) taken after 5 days of loading gave more power over a series of six 10-second sprints than creatine alone, on the early sprints.

The effect is not always additive. In 23 endurance athletes, men and women, creatine loading increased average power over a 15-second sprint (+34 watts), but adding 3 mg of caffeine per kilo brought no significant extra benefit (+10 watts). Caffeine, on the other hand, improved a 6-minute time trial (+12 watts), where creatine did nothing. In 24 men, caffeine increased peak power in the Wingate test (1,033 versus 1,003 watts), with or without creatine. Each supplement therefore keeps its own domain.

To know when caffeine really helps in bodybuilding, and at what dose, the article caffeine before bodybuilding takes stock.

Caffeine every day during loading: the doubt

This is the only case that raises questions, and the trials disagree. The largest one, on 54 active men, compared for 5 days a load of 20 g of creatine per day alone, with 300 mg of caffeine per day, with coffee (about 300 mg of caffeine) or a placebo. Strength increased in all groups, with no interaction. But creatine alone did no better than the placebo either, which limits what the trial can show.

In 28 trained young adults, six weeks of weight training with creatine (0.1 g per kilo per day), caffeine (3 mg per kilo per day), both, or a placebo: only the creatine group thickened the muscles at the front of the thigh. The creatine + caffeine group did not. No other difference in strength, endurance, or fatigue. This points towards an inhibitory effect, on a small sample size and a single result.

Why caffeine might inhibit creatine

Absorption is not to blame. The two reviews put forward two other tracks: opposite effects on how the muscle relaxes, and digestive issues when taking both at the same time (2022 review, 2015 review). In the trial on 54 men, four participants reported mild digestive discomfort with creatine and caffeine.

And for the brain?

In 12 resistance-trained men, seven days of creatine nitrate (5 g per day) with caffeine (400 mg per day) slightly improved an attention test compared to caffeine alone, without gaining anything on the bench press, leg press, or sprint. No adverse effects were reported. This is a trial on a specific form of creatine.

In summary

To see when to place each in your day and check interactions with your other supplements, My stack organizes them for you. And if you are still hesitating about the timing of creatine, the article when to take your supplements sorts it out.

Every number in this article comes from a study you can open: the underlined mentions lead to the summary of the work it is drawn from, written from the abstract alone. The trials are small and focus mostly on young men. Informative content, which does not replace the advice of a healthcare professional.