For the first time in 13 years, the U.S. Food and Drug Administration has approved two weight loss drugs. Nearly a year after both prescription drugs were approved, Belviq and Qsymia are available. They are designed to help adults with a body mass index of 30 or greater and who have a weight-related condition such as high blood pressure, type 2 diabetes or high cholesterol.

Qsymia is the combination of two FDA-approved drugs, phentermine and topiramate. The latter has helped treat migraine patients for years.

“Topiramate controls a portion of the brain that’s responsible for a feeling of fullness,” Dr. Cwynar told NBC Los Angeles. “It makes the stomach feel like it’s got enough food in there.”

But topiramate can make people feel drowsy. The drug’s second main ingredient, phentermine, combats this potential side effect.  

“Normal phenteramine on the market is 37 milligram; this has a 3 milligram as a starter dose. So it’s a fraction of what’s out there, and it doesn’t have the agitation or the cardiac effects,” Cwynar said. “I have had one patient who said it made her feel spacey, and she had a high-powered job, so she stopped it.” 

In its approval, the FDA points to a clinical trial that evaluated Qsymia’s effectiveness. It shows that out of 3,700 obese and overweight patients who took the pill for a year along with lifestyle changes had an average weight loss of 8.9 percent.  

On the drug’s official website, common side effects include numbness, dizziness, loss of taste and trouble sleeping, among others.

Unlike Qsymia, Belviq has had moderate success in its clinical trials. The drug works by activating the serotonin 2C receptor in the brain, which may help a person feel full after eating smaller amounts of food.

Belviq studies show patients lost 3 percent to 3.7 percent of their weight over the period of a year. Roughly 47 percent of patients without diabetes lost 5 percent of their weight, AP reports.

Analysts said both drugs will face marketing challenges. Qsymia sales have been disappointing despite that drug's superior results.

Scott Cameron Brown of Los Angeles experienced Qsymia’s effects firsthand. He was prescribed Qsymia when he was 40 pounds overweight and his health was in jeopardy. Along with a diet and exercise plan, Brown lost 40 pounds in four months.

“I feel rejuvenated, and I’m off in a whole new direction,” he told NBC Los Angeles. “I’m excited for the new direction of life.”