In the film “Limitless,” the main character, portrayed by Bradley Cooper, is given access to a mysterious drug that allows him to unlock the full use of his brain—an extremely useful ability considering humans only use about 10 percent of our brain's potential. Although the story was fictional, there is a similar drug that exists.

The drug is called NeuroFuse, and it's certainly not the first "smart drug" on the market with prescription drugs like Adderall, Ritalin and Dexedrine available. But NeuroFuse can be purchased online without a prescription and claims to immensely increase energy levels, sharpen the mind and boost brain power. Its ingredients include phosphatidylserine and DMAE Bitartrate, which are intended to strengthen brain activity. On the official website, there are several purchase plans available.

Although it has no history of side effects during clinical trials, there were complaints that the drug was too powerful to use without a regulated prescription. Due to outside pressures and criticism about the drug giving users an artificial edge, production of NeuroFuse was stopped.

However, after three years of clinical trials proving its safety, the company was allowed to resume production of the drug. On Amazon, the product is described as an “All herbal based neuro-support. Safely increase focus, energy and mental performance.”

Jason Mazanov, an international expert on drug management with the UNSW Canberra School of Business recently, told Huffington Post Australia that "Limitless" set unrealistic expectations about the drug’s performance.

"The evidence we have does not suggest that it can do what a lot of the mythology around these drugs actually suggest. When a healthy, person takes these drugs, what they might experience is that they overcome fatigue, or they have the ability to concentrate and focus on something really well," Mazanov said.

The effectiveness of the drug also depends on the mindset of the person and what they are focused on. "What can happen is, for example, you might want to do an assignment or work, but instead you focus on cleaning your house. It becomes difficult to get out of that track of thinking,” Mazanov explained.

Mazanov also noted that nootropic drugs are “questionable.” The Food and Drug Administration (FDA) does not review dietary supplements.