A great product for more of a cumulative and medium-term effect. I personally don’t see a huge difference right away (within a few hours like others have written), but have noticed greater focus when taken for a few days/weeks.
Legal Disclaimer: These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. My experience is personal and the effects are personal and different for everyone. Talk to your medical professional about adding any supplements to your diet.