It depends on several variables. But the current levels of your body's testosterone release will pull a lot of weight. Thus, for some people, the effect of Spartagen-XT can be sudden and dramatic. However, for others, the effect can be gradual and progressive. But, regardless of how dramatic or progressive your body's response is to the supplement, you can expect to feel more energized, upbeat and confident when the full effect of your improved testosterone level starts kicking in.