The evidence is mixed, but the preponderance of the evidence suggests that it’s unlikely that creatine will increase your testosterone levels.
Three randomized controlled trials conducted in healthy young men reported that supplementing with creatine for 1–3 weeks produced small increases in the levels of testosterone or dihydrotestosterone (DHT; a highly active androgen converted from testosterone).[1][2][3] One of the 3 trials looked at the effect of creatine loading (25 grams/day for 1 week) followed by a maintenance phase (5 grams/day for 2 weeks) on testosterone and DHT in 20 young, healthy rugby players. Although no effect on testosterone was found, creatine increased the levels of DHT by 12 nanograms of DHT per deciliter of blood (ng/dL).[1] The other 2 trials found that supplementation with creatine for 1 week in healthy, active young men increased the concentrations of testosterone by 57 ng/dL and 150 ng/dL.[2][3]
Conversely, 10 other trials (involving a total of 218 participants) looking at the effect of supplemental creatine at daily doses of 3–25 grams on testosterone levels for up to 12 weeks have found no statistically significant effect.[4][5][6][1][7][8][9][10][11][12] The participants in the majority of these trials were healthy, active young men. With regard to the form of creatine used, 9 trials administered creatine monohydrate, whereas 1 trial administered creatine malate. It’s worth noting that no trials have looked at the effect of creatine on testosterone in men with abnormally low testosterone levels.
Taken together, the available evidence suggests that supplementing with creatine is unlikely to increase testosterone levels, at least in young healthy men whose testosterone levels are within the normal range.